As filed with the Securities and Exchange Commission on October 4, 2001
                                                Registration No. 333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                      -------------------------------------
                                    FORM S-3
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933
                      -------------------------------------
                           ALLIANT ENERGY CORPORATION
             (Exact name of registrant as specified in its charter)
            Wisconsin                                         39-1380265
(State or other jurisdiction of                             (I.R.S. Employer
 incorporation or organization)                            Identification No.)

                           Alliant Energy Corporation
                           222 West Washington Avenue
                            Madison, Wisconsin 53703
                                 (608) 252-3311
       (Address, including zip code, and telephone number, including area
               code, of registrant's principal executive offices)
                      -------------------------------------
                                Edward M. Gleason
                Vice President-Treasurer and Corporate Secretary
                           Alliant Energy Corporation
                           222 West Washington Avenue
                            Madison, Wisconsin 53703
                                 (608) 252-3311
           (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)
                      -------------------------------------
                                 with a copy to:
      Benjamin F. Garmer, III, Esq.                  Barbara L. Becker, Esq.
            Foley & Lardner                        Gibson, Dunn & Crutcher LLP
       777 East Wisconsin Avenue                         200 Park Avenue
       Milwaukee, Wisconsin 53202                    New York, New York 10166
            (414) 271-2400                               (212) 351-4000
                      -------------------------------------
     Approximate date of commencement of proposed sale to the public: From time
to time after this registration statement becomes effective.
     If the only securities being registered on this Form are being offered
pursuant to dividend or interest reinvestment plans, please check the following
box. |_|
     If any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, please check the following box.|X|
     If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. |_|
     If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. |_|
     If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. |_|


                            CALCULATION OF REGISTRATION FEE
=====================================================================================
  Title of Each       Amount      Proposed Maximum  Proposed Maximum     Amount of
Class of Securities    to Be       Offering Price   Aggregate Offering  Registration
to Be Registered    Registered(1)   Per Share(2)        Price(2)            Fee
-------------------------------------------------------------------------------------
                                                              
Common Stock,
$.01 par value,       12,000,000        $30.225       $362,700,000.00     $90,675.00
with attached         shares
Common Share           and
Purchase Rights.....  rights
=====================================================================================
(1) Each share of Alliant Energy Corporation Common Stock has attached thereto one
    Common Share Purchase Right.
(2) Estimated solely for the purpose of calculating the registration fee pursuant to
    Rule 457(c) under the Securities Act of 1933, based on the average of the high and
    low prices of the Common Stock of Alliant Energy Corporation as reported on the
    New York Stock Exchange on September 27, 2001. The value attributable to the
    Rights is reflected in the price of the Common Stock.

                      -------------------------------------
     The Registrant hereby amends this Registration Statement on such date or
dates as may be necessary to delay its effective date until the Registrant shall
file a further amendment which specifically states that this Registration
Statement shall thereafter become effective in accordance with Section 8(a) of
the Securities Act of 1933 or until this Registration Statement shall become
effective on such date as the Commission, acting pursuant to said Section 8(a),
may determine.
================================================================================

The information in this prospectus is not complete and may be changed. We may
not sell these securities until the registration statement filed with the
Securities and Exchange Commission is effective. This prospectus is not an offer
to sell these securities and it is not soliciting an offer to buy these
securities in any state where this offer or sale is not permitted.


                  SUBJECT TO COMPLETION, DATED OCTOBER 4, 2001


                              [ALLIANT ENERGY LOGO]


                                12,000,000 Shares

                           Alliant Energy Corporation

                                  Common Stock

                            -------------------------

     By this prospectus, we may offer from time to time up to 12,000,000 shares
of our common stock. Our common stock is listed on the New York Stock Exchange
under the symbol "LNT."

     When we offer common stock, we will provide you with a prospectus
supplement describing the terms of the specific issue of common stock including
the offering price.

                            ------------------------

     You should read this prospectus and the prospectus supplement relating to
the specific issue of common stock carefully before you invest.

                            -------------------------

     Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or determined if this
prospectus is truthful or complete. Any representation to the contrary is a
criminal offense.

                            -------------------------



               The date of this prospectus is ____________, 2001.



                                TABLE OF CONTENTS

                                                                            Page

About This Prospectus........................................................ 2
Alliant Energy Corporation................................................... 3
Use of Proceeds.............................................................. 4
Price Range of Common Stock and Dividend Policy.............................. 4
Description of Common Stock.................................................. 5
Plan of Distribution......................................................... 7
Where You Can Find More Information.......................................... 7
Legal Matters................................................................ 8
Experts...................................................................... 8


                              ABOUT THIS PROSPECTUS

     This prospectus is part of a registration statement that we filed with the
Securities and Exchange Commission utilizing a "shelf" registration process.
Under this shelf process, we may, from time to time, sell the shares of our
common stock described in this prospectus in one or more offerings up to a total
number of 12,000,000 shares. This prospectus provides you with a general
description of the shares that we may offer. Each time we offer shares, we will
provide a prospectus supplement that will contain specific information about the
terms of that offering. The prospectus supplement may also add, update or change
information contained in this prospectus. You should read both this prospectus
and any prospectus supplement together with additional information described
under the heading "Where You Can Find More Information." Unless we otherwise
indicate or unless the context requires otherwise, all references in this
prospectus to "we," "our," "us" or similar references mean Alliant Energy
Corporation.


                                       2


                           ALLIANT ENERGY CORPORATION

     We are a public utility holding company with a diversified portfolio of
energy businesses. Our regulated public utility subsidiaries, Wisconsin Power
and Light Company, IES Utilities Inc. and Interstate Power Company, are engaged
principally in:

     o    the generation, transmission, distribution and sale of electric
          energy;

     o    the purchase, distribution, transportation and sale of natural gas;
          and

     o    water and steam services in selected markets.

The principal markets of our utility subsidiaries are located in Iowa,
Wisconsin, Minnesota and Illinois.

     Through our subsidiary, Alliant Energy Resources, Inc., we manage a
portfolio of companies involved in non-regulated businesses. These businesses
include:

     o    global partnerships to develop energy generation, delivery and
          infrastructure in growing international markets;

     o    domestic companies that provide integrated services, including energy,
          environmental, engineering and transportation services;

     o    Cargill-Alliant, LLC, our energy trading joint venture with Cargill
          Incorporated; and

     o    other investments, including our oil and natural gas operations.

     Our principal executive offices are located at 222 West Washington Avenue,
Madison, Wisconsin 53703, and our telephone number is (608) 252-3311.

                                 USE OF PROCEEDS

     Unless otherwise specified in the applicable prospectus supplement, we will
use the net proceeds from the sale of our common stock to make additional
capital contributions to our subsidiaries or to repay our debt or the debt of
our subsidiaries. Our subsidiaries may use these capital contributions for
financing the development and construction of new generation, transmission and
distribution facilities, funding additional working capital, financing capital
expenditures, funding potential acquisitions and investments and other general
corporate purposes. Until we use the net proceeds from the sale of common stock
for these purposes, we may use the net proceeds for temporary investments.


                                       3

                 PRICE RANGE OF COMMON STOCK AND DIVIDEND POLICY

     Our common stock is listed on the New York Stock Exchange under the symbol
"LNT." The following table shows the high and low reported closing sale prices
of the common stock on the New York Stock Exchange for the stated calendar
quarter.
                                                       Price of Common Stock
                                                       ---------------------
                                                         High           Low
                                                         ----           ---

     2001      First Quarter..........................  $33.20        $28.75
               Second Quarter.........................   32.67         28.20
               Third Quarter..........................   31.49         27.90

     2000      First Quarter..........................  $37.75        $26.44
               Second Quarter.........................   31.88         25.75
               Third Quarter..........................   31.25         26.13
               Fourth Quarter.........................   32.13         28.63

     1999      First Quarter..........................  $32.38        $26.38
               Second Quarter.........................   30.88         26.50
               Third Quarter..........................   30.06         26.75
               Fourth Quarter.........................   28.81         25.19

     In 1999, 2000 and the first two quarters of 2001, we paid quarterly cash
dividends of $0.50 per share of our common stock.

     We currently intend to declare and pay dividends on a regular basis at the
current rate. However, the payment and amount of future dividends is at the
discretion of our board of directors and will depend upon our future earnings,
capital requirements, and general financial condition, general business
conditions, the ability of our subsidiaries to pay dividends to us and other
factors. Our primary source of funds for the payment of dividends to our
shareowners is dividends our subsidiaries pay to us. Our utility subsidiaries
each have restrictions on the payment of dividends on their common stock based
on their respective bond indentures, the terms of their outstanding preferred
stock and regulatory restrictions applicable to them.


                                       4

                           DESCRIPTION OF COMMON STOCK

     Our articles of incorporation provide that we have authority to issue
200,000,000 shares of common stock. The Securities and Exchange Commission has
authorized us under the Public Utility Holding Company Act of 1935 to issue the
shares to be offered pursuant to this prospectus.

     The following summary of some provisions of our common stock is not
complete. You should refer to our articles of incorporation and our rights
agreement, which are incorporated by reference as exhibits to the registration
statement of which this prospectus is a part, and applicable law for more
information.

Common Stock

     All of the issued and outstanding shares of our common stock are fully paid
and nonassessable, and the shares of common stock being sold by us will, upon
completion of the offering, be fully paid and nonassessable, except in each case
for statutory liability under Section 180.0622(2)(b) of the Wisconsin Business
Corporation Law for unpaid employee wages.

     Our common stock is entitled to such dividends as may be declared from time
to time by our board of directors in accordance with applicable law. Our ability
to pay dividends is dependent upon a number of factors, including the ability of
our subsidiaries to pay dividends to us. Our utility subsidiaries each have
restrictions on the payment of dividends on their common stock based on their
respective bond indentures, the terms of their outstanding preferred stock and
regulatory restrictions applicable to them.

     Except as provided under Wisconsin law, only the holders of common stock
will be entitled to vote for the election of members to our board of directors
and on all other matters. Holders of our common stock are entitled to one vote
per share of common stock held by them on all matters properly submitted to a
vote of shareowners, subject to Section 180.1150 of the Wisconsin Business
Corporation Law. See "- Statutory Provisions." Shareowners have no cumulative
voting rights, which means that the holders of shares entitled to exercise more
than 50% of the voting power are able to elect all of the directors to be
elected. Our board of directors is divided into three classes, with staggered
terms of three years each.

     All shares of common stock are entitled to participate equally in
distributions in liquidation. Holders of common stock have no preemptive rights
to subscribe for or purchase our shares. There are no conversion rights, sinking
fund or redemption provisions applicable to our common stock. We do not have the
authority to issue any shares of preferred stock.

     The transfer agent for our common stock is our subsidiary, Alliant Energy
Corporate Services, Inc.

Common Share Purchase Rights

     We have entered into a rights agreement pursuant to which each outstanding
share of our common stock, including those shares being sold by us pursuant to
this prospectus, has attached a right to purchase one-half of one share of our
common stock. Each share of our common stock subsequently issued by us prior to
the expiration of the rights agreement will likewise have attached a right.
Under circumstances described below, the rights will entitle the holder of the
rights to purchase additional shares of our common stock. In this prospectus and
any accompanying prospectus supplement, unless the context requires otherwise,
all references to our common stock include the accompanying rights.

     Currently, the rights are not exercisable and trade with our common stock.
If the rights become exercisable, each full right, unless held by a person or
group that beneficially owns more than 15% of our outstanding common stock, will
initially entitle the holder to purchase one half of one share of our common
stock at a purchase price of $95 per full share, or $47.50 per half share,
subject to adjustment. The rights will become exercisable only if a person or
group has acquired, or announced an intention to acquire, 15% or more of our
outstanding common stock. Under some circumstances, including the existence of a
15% acquiring party, each holder of a right, other than the acquiring party,
will be entitled to purchase at the right's then-current exercise price, shares
of our common stock

                                       5

having a market value of two times the exercise price. If another corporation
acquires us after a party acquires 15% or more of our common stock, each holder
of a right will be entitled to receive the acquiring corporation's common shares
having a market value of two times the exercise price. The rights may be
redeemed at a price of $0.001 until a party acquires 15% or more of our common
stock and, after that time, may be exchanged for one share of our common stock
per right until a party acquires 50% or more of our common stock. The rights
expire on January 20, 2009, subject to extension. Under the rights agreement,
our board of directors may reduce the thresholds applicable to the rights from
15% to not less than 10%. The rights do not have voting or dividend rights and,
until they become exercisable, have no dilutive effect on our earnings.

Statutory Provisions

     Because we are a public utility holding company under the Public Utility
Holding Company Act of 1935, the SEC must approve the acquisition of any of our
securities or utility assets by a registered public utility holding company or
any person who would, as a result of such acquisition, become an affiliate of
two or more public utility companies.

     Section 180.1150 of the Wisconsin Business Corporation Law provides that
the voting power of public Wisconsin corporations such as us held by any person
or persons acting as a group in excess of 20% of our voting power is limited to
10% of the full voting power of those shares, unless full voting power of those
shares has been restored pursuant to a vote of shareowners. Sections 180.1140 to
180.1144 of the Wisconsin Business Corporation Law contain some limitations and
special voting provisions applicable to specified business combinations
involving Wisconsin corporations such as us and a significant shareholder,
unless the board of directors of the corporation approves the business
combination or the shareholder's acquisition of shares before these shares are
acquired.

     Similarly, Sections 180.1130 to 180.1133 of the Wisconsin Business
Corporation Law contain special voting provisions applicable to some business
combinations, unless specified minimum price and procedural requirements are
met. Following commencement of a takeover offer, Section 180.1134 of the
Wisconsin Business Corporation Law imposes special voting requirements on share
repurchases effected at a premium to the market and on asset sales by the
corporation, unless, as it relates to the potential sale of assets, the
corporation has at least three independent directors and a majority of the
independent directors vote not to have the provision apply to the corporation.

     Section 196.795(3) of the Wisconsin Statutes provides that no person may
hold or acquire directly or indirectly more than 10% of the outstanding
securities of a public utility holding company such as us without the approval
of the Public Service Commission of Wisconsin.


                                       6

                              PLAN OF DISTRIBUTION

     We may sell the common stock being offered hereby in one or more of the
following ways from time to time:

     o    to underwriters for resale to the public or to institutional
          investors;

     o    directly to institutional investors;

     o    directly to agents;

     o    through agents to the public or to institutional investors; or

     o    if indicated in the prospectus supplement, pursuant to delayed
          delivery contracts, by remarketing firms or by other means.

     The prospectus supplements will set forth the terms of the offering of
common stock, including the name or names of any underwriters or agents, the
purchase price of the common stock and the proceeds to us from the sale, any
underwriting discounts or agency fees and other items constituting underwriters'
or agents' compensation and any discounts or concessions allowed or reallowed or
paid to dealers.

     If underwriters are utilized in the sale, the common stock will be acquired
by the underwriters for their own account under an underwriting agreement that
we will execute with the underwriters at the time an agreement for such sale is
reached, and may be resold from time to time in one or more transactions,
including negotiated transactions, at a fixed public offering price or prices,
which may be changed, or at market or varying prices determined at the time of
sale.

     Unless otherwise set forth in a prospectus supplement, the obligations of
the underwriters to purchase common stock will be subject to conditions
precedent and the underwriters will be obligated to purchase all of the common
stock if any is purchased.

     If a dealer is utilized in the sale of the common stock, we will sell the
common stock to the dealer, as principal. The dealer may then resell the common
stock to the public at varying prices to be determined by the dealer at the time
of resale.

     Underwriters, agents and dealers may be entitled under agreements entered
into with us to be indemnified by us against civil liabilities, including
liabilities under the Securities Act of 1933, or to contribution with respect to
payments which the underwriters or agents may be required to make in respect
thereof. Underwriters, agents and dealers may be customers of, engage in
transactions with, or perform services for us and our subsidiaries and
affiliates in the ordinary course of business.

                       WHERE YOU CAN FIND MORE INFORMATION

     We file annual, quarterly and current reports, proxy statements and other
information with the SEC. We have also filed a registration statement on Form
S-3, including exhibits, under the Securities Act of 1933 with respect to the
common stock offered by this prospectus. This prospectus is a part of the
registration statement, but does not contain all of the information included in
the registration or the exhibits. You may read and copy the registration
statement and any other document which we file at the SEC's public reference
rooms at 450 Fifth Street, N.W., Washington D.C., and at regional SEC offices in
Chicago, Illinois. You can call the SEC at 1-800-SEC-0330 for further
information on the operation of the public reference rooms. You can also find
our public filings with the SEC on the internet at a web site maintained by the
SEC located at http://www.sec.gov.


                                       7


     We are "incorporating by reference" specified documents that we file with
the SEC, which means:

     o    incorporated documents are considered part of this prospectus;

     o    we are disclosing important information to you by referring you to
          those documents; and

     o    information we file with the SEC will automatically update and
          supersede information contained in this prospectus.

     We incorporate by reference the documents we list below and any future
filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the
Securities Exchange Act of 1934 after the date of this prospectus and before the
end of the offering of our common stock:

     o    our Annual Report on Form 10-K for the year ended December 31, 2000;

     o    our Quarterly Reports on Form 10-Q for the quarters ended March 31,
          2001 and June 30, 2001;

     o    our Current Report on Form 8-K, dated February 20, 2001 and filed
          February 20, 2001, as amended by our Current Report on Form 8-K/A,
          dated February 20, 2001 and filed March 1, 2001;

     o    the description of our common stock contained in our Registration
          Statement on Form 8-B, dated April 1, 1988, and any amendment or
          report updating that description; and

     o    the description of our common share purchase rights contained in our
          Registration Statement on Form 8-A, dated January 20, 1999, and any
          amendment or report updating that description.

     You may request a copy of any of these filings, at no cost, by writing to
Edward M. Gleason, Vice President-Treasurer and Corporate Secretary, Alliant
Energy Corporation, 222 West Washington Avenue, Madison, Wisconsin 53703, or by
calling Mr. Gleason at (608) 252-3311.

                                  LEGAL MATTERS

     The validity of the shares of our common stock offered by this prospectus
will be passed upon for us by Foley & Lardner, Milwaukee, Wisconsin. Some legal
matters will be passed upon for the underwriters, dealers, purchasers or agents
by Gibson, Dunn & Crutcher LLP, New York, New York.

                                     EXPERTS

     The audited financial statements and schedules incorporated by reference in
this prospectus and elsewhere in the registration statement have been audited by
Arthur Andersen LLP, independent public accountants, as indicated in their
report with respect thereto, and are included herein in reliance upon the
authority of said firm as experts in accounting and auditing in giving said
report.

                                       8

                                     PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.

         Securities and Exchange Commission filing fee..........  $    90,090
         Legal fees and expenses................................      125,000
         New York Stock Exchange listing fees...................       50,000
         Accounting fees and expenses...........................       40,000
         Printing and engraving expenses........................       75,000
         Miscellaneous..........................................       44,910
                                                                  -----------
              Total expenses....................................  $   425,000
                                                                  ===========

     All of the above fees and expenses will be paid by Alliant Energy
Corporation (the "Registrant"). Other than the Securities and Exchange
Commission filing fee, all fees and expenses are estimated.

Item 15. Indemnification of Directors and Officers.

     Pursuant to the provisions of the Wisconsin Business Corporation Law and
Article VIII of the Registrant's Bylaws, directors and officers of the
Registrant are entitled to mandatory indemnification from the Registrants
against certain liabilities (which may include liabilities under the Securities
Act of 1933) and expenses (i) to the extent such officers or directors are
successful in the defense of a proceeding; and (ii) in proceedings in which the
director or officer is not successful in defense thereof, unless it is
determined that the director or officer breached or failed to perform his or her
duties to the Registrant and such breach or failure constituted: (a) a willful
failure to deal fairly with the Registrant or its shareowners in connection with
a matter in which the director or officer had a material conflict of interest;
(b) a violation of criminal law unless the director or officer had a reasonable
cause to believe his or her conduct was lawful or had no reasonable cause to
believe his or her conduct was unlawful; (c) a transaction from which the
director or officer derived an improper personal profit; or (d) willful
misconduct. Additionally, under the Wisconsin Business Corporation Law,
directors of the Registrant are not subject to personal liability to the
Registrant, its shareowners or any person asserting rights on behalf thereof,
for certain breaches or failures to perform any duty resulting solely from their
status as directors, except in circumstances paralleling those outlined in (a)
through (d) above.

     The indemnification provided by the Wisconsin Business Corporation Law and
the Registrant's Bylaws is not exclusive of any other rights to which a director
or officer of the Registrant may be entitled. The Registrants also carries
directors' and officers' liability insurance.

Item 16. Exhibits and Financial Statement Schedules.

     The exhibits listed in the accompanying Exhibit Index are filed or
incorporated by reference as part of this Registration Statement.

Item 17. Undertakings.

     (a) The undersigned Registrant hereby undertakes:

       (1) To file, during any period in which offers or sales are being made, a
          post-effective amendment to this Registration Statement:

          (i)  To include any prospectus required by Section 10(a)(3) of the
               Securities Act of 1933;

          (ii) To reflect in the prospectus any facts or events arising after
               the effective date of the Registration Statement (or the most
               recent post-effective amendment thereof)

                                      II-1

               which, individually or in the aggregate, represent a fundamental
               change in the information set forth in the Registration
               Statement. Notwithstanding the foregoing, any increase or
               decrease in volume of securities offered (if the total dollar
               value of securities offered would not exceed that which was
               registered) and any deviation from the low or high end of the
               estimated maximum offering range may be reflected in the form of
               prospectus filed with the Commission pursuant to Rule 424(b) if,
               in the aggregate, the changes in volume and price represent no
               more than a 20% change in the maximum aggregate offering price
               set forth in the "Calculation of Registration Fee" table in the
               effective Registration Statement;

          (iii)To include any material information with respect to the plan of
               distribution not previously disclosed in the Registration
               Statement or any material change to such information in the
               Registration Statement;

               provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do
               not apply if the information required to be included in a
               post-effective amendment by those paragraphs is contained in
               periodic reports filed by the Registrant pursuant to Section 13
               or Section 15(d) of the Securities Exchange Act of 1934 that are
               incorporated by reference in the Registration Statement.

       (2) That, for the purpose of determining any liability under the
           Securities Act of 1933, each such post-effective amendment shall be
           deemed to be a new Registration Statement relating to the securities
           offered therein, and the offering of such securities at that time
           shall be deemed to be the initial bona fide offering thereof.

       (3) To remove from registration by means of a post-effective amendment
           any of the securities being registered which remain unsold at the
           termination of the offering.

     (b)  The undersigned Registrant hereby undertakes that, for purposes of
          determining any liability under the Securities Act of 1933, each
          filing of the Registrant's annual report pursuant to Section 13(a) or
          Section 15(d) of the Securities Exchange Act of 1934 that is
          incorporated by reference in the Registration Statement shall be
          deemed to be a new Registration Statement relating to the securities
          offered therein, and the offering of such securities at that time
          shall be deemed to be the initial bona fide offering thereof.

     (c)  Insofar as indemnification for liabilities arising under the
          Securities Act of 1933 may be permitted to directors, officers and
          controlling persons of the Registrant pursuant to the provisions set
          forth or described in Item 15 of this Registration Statement, or
          otherwise, the Registrant has been advised that in the opinion of the
          Securities and Exchange Commission such indemnification is against
          public policy as expressed in the Securities Act of 1933 and is,
          therefore, unenforceable. In the event that a claim for
          indemnification against such liabilities (other than the payment by
          the Registrant of expenses incurred or paid by a director, officer or
          controlling person of the Registrant in the successful defense
          of any action, suit or proceeding) is asserted by such director,
          officer or controlling person in connection with the securities being
          registered, the Registrant will, unless in the opinion of its counsel
          the matter has been settled by controlling precedent, submit to a
          court of appropriate jurisdiction the question whether such
          indemnification by it is against public policy as expressed in the
          Securities Act of 1933 and will be governed by the final adjudication
          of such issue.

     (d)  The undersigned registrant hereby undertakes that:

        (1) For purposes of determining any liability under the Securities
            Act of 1933, the information omitted from the form of prospectus
            filed as part of this Registration Statement in reliance upon
            Rule 430A and contained in a form of prospectus filed by the
            Registrant pursuant to Rule 424(b)(1) or (4) or 497(h) under the
            Securities Act shall be deemed to be part of this Registration
            Statement as of the time it was declared effective.
                                      II-2


        (2)  For the purpose of determining any liability under the Securities
             Act of 1933, each post-effective amendment that contains a form
             of prospectus shall be deemed to be a new Registration Statement
             relating to the securities offered therein, and the offering of
             such securities at that time shall be deemed to be the initial
             bona fide offering thereof.



                                      II-3

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-3 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Madison, State of Wisconsin, on October 4, 2001.

                                        ALLIANT ENERGY CORPORATION


                                        By: /s/ Erroll B. Davis, Jr.
                                            -----------------------------------
                                            Erroll B. Davis, Jr.
                                            Chairman, President and Chief
                                              Executive Officer

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.

        Signature                      Title                       Date
        ---------                      -----                       ----


/s/ Erroll B. Davis, Jr.    Chairman, President and Chief     October 4, 2001
--------------------------- Executive Officer and Director
Erroll B. Davis, Jr.        (Principal Executive Officer)


/s/ Thomas M. Walker        Executive Vice President and      October 4, 2001
--------------------------- Chief Financial Officer
Thomas M. Walker            (Principal Financial Officer)


/s/ John E. Kratchmer       Corporate Controller and Chief    October 4, 2001
--------------------------- Accounting Officer (Principal
John E. Kratchmer           Accounting Officer)


            *
---------------------------  Director                         October 4, 2001
Alan B. Arends


            *
--------------------------- Director                          October 4, 2001
Jack B. Evans


            *               Director                          October 4, 2001
---------------------------
Joyce L. Hanes


            *               Director                          October 4, 2001
---------------------------
Lee Liu


            *               Director                          October 4, 2001
---------------------------
Katharine C. Lyall


            *               Director                          October 4, 2001
---------------------------
Singleton B. McAllister


                                      S-1


        Signature                      Title                       Date
        ---------                      -----                       ----


            *               Director                          October 4, 2001
---------------------------
David A. Perdue


            *               Director                          October 4, 2001
---------------------------
Judith D. Pyle


            *               Director                          October 4, 2001
---------------------------
Robert W. Schlutz


            *               Director                          October 4, 2001
---------------------------
Wayne H. Stoppelmoor


            *               Director                          October 4, 2001
---------------------------
Anthony R. Weiler


*By: /s/ Erroll B. Davis, Jr.
    -------------------------
     Erroll B. Davis, Jr.
     Attorney-in-fact



                                      S-2

                                  EXHIBIT INDEX

Exhibit
-------
Number                       Document Description
------                       --------------------

(1)       Form of Underwriting Agreement.*

(4.1)     Restated Articles of Incorporation of Alliant Energy Corporation, as
          amended (incorporated by reference to Exhibit 3.2 to Registrant's
          Quarterly Report on Form 10-Q for the quarter ended June 30, 1999).

(4.2)     Rights Agreement, dated January 20, 1999, between Alliant Energy
          Corporation and Firstar Bank Milwaukee, N.A. (incorporated by
          reference to Exhibit 4.1 to Alliant Energy Corporation's Registration
          Statement on Form 8-A, dated January 20, 1999).

(4.3)     Indenture of Mortgage or Deed of Trust dated August 1, 1941, between
          Wisconsin Power and Light Company ("WP&L") and First Wisconsin Trust
          Company (n/k/a Firstar Bank, N.A.) and George B. Luhman, as Trustees,
          filed as Exhibit 7(a) in File No. 2-6409, and the indentures
          supplemental thereto dated, respectively, January 1, 1948, September
          1, 1948, June 1, 1950, April 1, 1951, April 1, 1952, September 1,
          1953, October 1, 1954, March 1, 1959, May 1, 1962, August 1, 1968,
          June 1, 1969, October 1, 1970, July 1, 1971, April 1, 1974, December
          1, 1975, May 1, 1976, May 15, 1978, August 1, 1980, January 15, 1981,
          August 1, 1984, January 15, 1986, June 1, 1986, August 1, 1988,
          December 1, 1990, September 1, 1991, October 1, 1991, March 1, 1992,
          May 1, 1992, June 1, 1992 and July 1, 1992 (Second Amended Exhibit
          7(b) in File No. 2-7361; Amended Exhibit 7(c) in File No. 2-7628;
          Amended Exhibit 7.02 in File No. 2-8462; Amended Exhibit 7.02 in File
          No. 2-8882; Second Amendment Exhibit 4.03 in File No. 2-9526; Amended
          Exhibit 4.03 in File No. 2-10406; Amended Exhibit 2.02 in File No.
          2-11130; Amended Exhibit 2.02 in File No. 2-14816; Amended Exhibit
          2.02 in File No. 2-20372; Amended Exhibit 2.02 in File No. 2-29738;
          Amended Exhibit 2.02 in File No. 2-32947; Amended Exhibit 2.02 in File
          No. 2-38304; Amended Exhibit 2.02 in File No. 2-40802; Amended Exhibit
          2.02 in File No. 2-50308; Exhibit 2.01(a) in File No. 2-57775; Amended
          Exhibit 2.02 in File No. 2-56036; Amended Exhibit 2.02 in File No.
          2-61439; Exhibit 4.02 in File No. 2-70534; Amended Exhibit 4.03 File
          No. 2-70534; Exhibit 4.02 in File No. 33-2579; Amended Exhibit 4.03 in
          File No. 33-2579; Amended Exhibit 4.02 in File No. 33-4961; Exhibit 4B
          to WP&L's Form 10-K for the year ended December 31, 1988, Exhibit 4.1
          to WP&L's Form 8-K dated December 10, 1990, Amended Exhibit 4.26 in
          File No. 33-45726, Amended Exhibit 4.27 in File No. 33-45726, Exhibit
          4.1 to WP&L's Form 8-K dated March 9, 1992, Exhibit 4.1 to WP&L's Form
          8-K dated May 12, 1992, Exhibit 4.1 to WP&L's Form 8-K dated June 29,
          1992 and Exhibit 4.1 to WP&L's Form 8-K dated July 20, 1992).

(4.4)     Indenture, dated as of June 20, 1997, between WP&L and Firstar Trust
          Company (n/k/a Firstar Bank, N.A.), as Trustee, relating to debt
          securities (incorporated by reference to Exhibit 4.33 to Amendment No.
          2 to WP&L's Registration Statement on Form S-3 (Registration No.
          33-60917)).

------------------
* To be filed by amendment or under subsequent Current Report on Form 8-K.

                                      E-1

Exhibit
-------
Number                       Document Description
------                       --------------------

(4.5)     Officers' Certificate, dated as of June 25, 1997, creating WP&L's 7%
          debentures due June 15, 2007 (incorporated by reference to Exhibit 4
          to WP&L's Current Report on Form 8-K, dated June 25, 1997).

(4.6)     Officers' Certificate, dated as of October 27, 1998, creating WP&L's
          5.70% debentures due October 15, 2008 (incorporated by reference to
          Exhibit 4 to WP&L's Current Report on Form 8-K, dated October 27,
          1998).

(4.7)     Officers' Certificate, dated as of March 1, 2000, creating WP&L's
          7-5/8% debentures due March 1, 2010 (incorporated by reference to
          Exhibit 4 to WP&L's Current Report on Form 8-K, dated March 1, 2000).

(4.8)     Indenture of Mortgage and Deed of Trust, dated as of September 1,
          1993, between IES Utilities Inc. ("IESU") (formerly Iowa Electric
          Light and Power Company ("IE")) and The First National Bank of
          Chicago, as Trustee ("Mortgage") (incorporated by reference to Exhibit
          4(c) to IESU's Form 10-Q for the quarter ended September 30, 1993).

(4.9)     Supplemental Indentures to IESU's 1993 Mortgage:

                                           IESU/IES Industries Inc.
            Number        Dated as of         File Reference           Exhibit
          ------------   ----------------  ------------------------    -------
          First          October 1, 1993      Form 10-Q, 11/12/93       4(d)
          Second         November 1, 1993     Form 10-Q, 11/12/93       4(e)
          Third          March 1, 1995        Form 10-Q, 5/12/95        4(b)
          Fourth         September 1, 1996    Form 8-K, 9/19/96         4(c)(i)
          Fifth          April 1, 1997        Form 10-Q, 5/14/97        4(a)

(4.10)    Indenture of Mortgage and Deed of Trust, dated as of August 1, 1940,
          between IESU (formerly IE) and The First National Bank of Chicago,
          Trustee ("1940 Indenture") (incorporated by reference to Exhibit 2(a)
          to IESU's Registration Statement, File No. 2-25347).

(4.11)    Supplemental Indentures to IESU's 1940 Indenture:

                                                       IESU
             Number            Dated as of         File Reference       Exhibit
          --------------   --------------------  ---------------------  -------
          First            March 1, 1941         2-25347                   2(a)
          Second           July 15, 1942         2-25347                   2(a)
          Third            August 2, 1943        2-25347                   2(a)
          Fourth           August 10, 1944       2-25347                   2(a)
          Fifth            November 10, 1944     2-25347                   2(a)
          Sixth            August 8, 1945        2-25347                   2(a)
          Seventh          July 1, 1946          2-25347                   2(a)
          Eighth           July 1, 1947          2-25347                   2(a)
          Ninth            December 15, 1948     2-25347                   2(a)
          Tenth            November 1, 1949      2-25347                   2(a)
          Eleventh         November 10, 1950     2-25347                   2(a)
          Twelfth          October 1, 1951       2-25347                   2(a)
          Thirteenth       March 1, 1952         2-25347                   2(a)

                                      E-2

Exhibit
-------
Number                       Document Description
------                       --------------------

          Fourteenth       November 5, 1952      2-25347                   2(a)
          Fifteenth        February 1, 1953      2-25347                   2(a)
          Sixteenth        May 1, 1953           2-25347                   2(a)
          Seventeenth      November 3, 1953      2-25347                   2(a)
          Eighteenth       November 8, 1954      2-25347                   2(a)
          Nineteenth       January 1, 1955       2-25347                   2(a)
          Twentieth        November 1, 1955      2-25347                   2(a)
          Twenty-first     November 9, 1956      2-25347                   2(a)
          Twenty-second    November 6, 1957      2-25347                   2(a)
          Twenty-third     November 4, 1958      2-25347                   2(a)
          Twenty-fourth    November 3, 1959      2-25347                   2(a)
          Twenty-fifth     November 1, 1960      2-25347                   2(a)
          Twenty-sixth     January 1, 1961       2-25347                   2(a)
          Twenty-seventh   November 7, 1961      2-25347                   2(a)
          Twenty-eighth    November 6, 1962      2-25347                   2(a)
          Twenty-ninth     November 5, 1963      2-25347                   2(a)
          Thirtieth        November 4, 1964      2-25347                   2(a)
          Thirty-first     November 2, 1965      2-25347                   2(a)
          Thirty-second    September 1, 1966     Form 10-K, 1966           4.10
          Thirty-third     November 30, 1966     Form 10-K, 1966           4.10
          Thirty-fourth    November 7, 1967      Form 10-K, 1967           4.10
          Thirty-fifth     November 5, 1968      Form 10-K, 1968           4.10
          Thirty-sixth     November 1, 1969      Form 10-K, 1969           4.10
          Thirty-seventh   December 1, 1970      Form 8-K, 12/70           1
          Thirty-eighth    November 2, 1971      2-43131                   2(g)
          Thirty-ninth     May 1, 1972           Form 8-K, 5/72            1
          Fortieth         November 7, 1972      2-56078                   2(i)
          Forty-first      November 7, 1973      2-56078                   2(j)
          Forty-second     September 10, 1974    2-56078                   2(k)
          Forty-third      November 5, 1975      2-56078                   2(l)
          Forty-fourth     July 1, 1976          Form 8-K, 7/76            1
          Forty-fifth      November 1, 1976      Form 8-K, 12/76           1
          Forty-sixth      December 1, 1977      2-60040                   2(o)
          Forty-seventh    November 1, 1978      Form 10-Q, 6/30/79        1
          Forty-eighth     December 1, 1979      Form S-16, 2-65996        2(q)
          Forty-ninth      November 1, 1981      Form 10-Q, 3/31/82        2
          Fiftieth         December 1, 1980      Form 10-K, 1981           4(s)
          Fifty-first      December 1, 1982      Form 10-K, 1982           4(t)
          Fifty-second     December 1, 1983      Form 10-K, 1983           4(u)
          Fifty-third      December 1, 1984      Form 10-K, 1984           4(v)
          Fifty-fourth     March 1, 1985         Form 10-K, 1984           4(w)
          Fifty-fifth      March 1, 1988         Form 10-Q, 5/12/88        4(b)
          Fifty-sixth      October 1, 1988       Form 10-Q, 11/10/88       4(c)
          Fifty-seventh    May 1, 1991           Form 10-Q, 8/13/91        4(d)
          Fifty-eighth     March 1, 1992         Form 10-K, 1991           4(c)
          Fifty-ninth      October 1, 1993       Form 10-Q, 11/12/93       4(a)
          Sixtieth         November 1, 1993      Form 10-Q, 11/12/93       4(b)
          Sixty-first      March 1, 1995         Form 10-Q, 5/12/95        4(a)
          Sixty-second     September 1, 1996     Form 8-K, 9/19/96         4(f)
          Sixty-third      April 1, 1997         Form 10-Q, 5/14/97        4(b)

                                      E-3

Exhibit
-------
Number                       Document Description
------                       --------------------

(4.12)    Indenture or Deed of Trust dated as of February 1, 1923, between IESU
          (successor to Iowa Southern Utilities Company ("IS") as result of
          merger of IS and IE) and The Northern Trust Company (The First
          National Bank of Chicago, successor) and Harold H. Rockwell (Richard
          D. Manella, successor), as Trustees (1923 Indenture) (incorporated by
          reference to Exhibit B-1 to File No. 2-1719).

(4.13)    Supplemental Indentures to IESU's 1923 Indenture:

                   Dated as of           File Reference            Exhibit
          -------------------------    ---------------------    ------------
          May 1, 1940                  2-4921                   B-1-k
          May 2, 1940                  2-4921                   B-1-l
          October 1, 1945              2-8053                   7(m)
          October 2, 1945              2-8053                   7(n)
          January 1, 1948              2-8053                   7(o)
          September 1, 1950            33-3995                  4(e)
          February 1, 1953             2-10543                  4(b)
          October 2, 1953              2-10543                  4(q)
          August 1, 1957               2-13496                  2(b)
          September 1, 1962            2-20667                  2(b)
          June 1, 1967                 2-26478                  2(b)
          February 1, 1973             2-46530                  2(b)
          February 1, 1975             2-53860                  2(aa)
          July 1, 1975                 2-54285                  2(bb)
          September 2, 1975            2-57510                  2(bb)
          March 10, 1976               2-57510                  2(cc)
          February 1, 1977             2-60276                  2(ee)
          January 1, 1978              0-849                    2
          March 1, 1979                0-849                    2
          March 1, 1980                0-849                    2
          May 31, 1986                 33-3995                  4(g)
          July 1, 1991                 0-849                    4(h)
          September 1, 1992            0-849                    4(m)
          December 1, 1994             0-4117-1                 4(f)

(4.14)    Indenture (For Unsecured Subordinated Debt Securities), dated as of
          December 1, 1995, between IESU and The First National Bank of Chicago,
          as Trustee (Subordinated Indenture) (incorporated by reference to
          Exhibit 4(i) to IESU's Amendment No. 1 to Registration Statement, File
          No. 33-62259).

(4.15)    Indenture (For Senior Unsecured Debt Securities), dated as of August
          1, 1997, between IESU and The First National Bank of Chicago, as
          Trustee (incorporated by reference to Exhibit 4(j) to IESU's
          Registration Statement, File No. 333-32097).

(4.16)    Officers' Certificate, dated as of August 4, 1997, creating IESU's
          6-5/8% Senior Debentures, Series A, due 2009 (incorporated by
          reference to Exhibit 4.12 to IESU's Annual Report on Form 10-K, for
          the year ended December 31, 2000).

                                      E-4

Exhibit
-------
Number                       Document Description
------                       --------------------

(4.17)    Officers' Certificate, dated as of March 6, 2001, creating IESU's
          6-3/4% Senior Debentures, Series B, due 2011 (incorporated by
          reference to Exhibit 4 to IESU's Current Report on Form 8-K, dated
          March 6, 2001).

(4.18)    The Original through the Nineteenth Supplemental Indentures of
          Interstate Power Company ("IPC") to The Chase Manhattan Bank and Carl
          E. Buckley and C. J. Heinzelmann, as Trustees, dated January 1, 1948
          securing First Mortgage Bonds (incorporated by reference to Exhibits
          4(b) through 4(t) to IPC's Registration Statement No. 33-59352 dated
          March 11, 1993).

(4.19)    Twentieth Supplemental Indenture of IPC to The Chase Manhattan Bank
          and C. J. Heinzelmann, as Trustees, dated May 15, 1993 (incorporated
          by reference to Exhibit 4(u) to IPC's Registration Statement No.
          33-59352 dated March 11, 1993).

(4.20)    Indenture, dated as of November 4, 1999, among Alliant Energy
          Resources, Inc., Alliant Energy Corporation, as Guarantor, and Firstar
          Bank, N.A., as Trustee (incorporated by reference to Exhibit 4.1 to
          Alliant Energy Resources, Inc.'s and Alliant Energy Corporation's
          Registration Statement on Form S-4 (Reg. No. 333-92859)).

(4.21)    First Supplemental Indenture, dated as of November 4, 1999, among
          Alliant Energy Resources, Inc., Alliant Energy Corporation, as
          Guarantor, and Firstar Bank, N.A., as Trustee (incorporated by
          reference to Exhibit 4.2 to Alliant Energy Resources, Inc.'s and
          Alliant Energy Corporation's Registration Statement on Form S-4 (Reg.
          No. 333-92859)).

(4.22)    Second Supplemental Indenture, dated as of February 1, 2000, among
          Alliant Energy Resources, Inc., Alliant Energy Corporation, as
          Guarantor, and Firstar Bank, N.A., as Trustee (incorporated by
          reference to Exhibit 99.4 to Alliant Energy Corporation's Current
          Report on Form 8-K dated February 1, 2000).

(5)       Opinion of Foley & Lardner (including consent of counsel).

(23.1)    Consent of Arthur Andersen LLP.

(23.2)    Consent of Foley & Lardner (filed as part of Exhibit (5)).

(24)      Powers of attorney.

Documents incorporated by reference to filings made by Alliant Energy
Corporation under the Securities Exchange Act of 1934, as amended, are under
File No. 1-9894. Documents incorporated by reference to filings made by
Wisconsin Power and Light Company under the Securities Exchange Act of 1934, as
amended, are under File No. 0-337. Documents incorporated by reference to
filings made by IES Industries Inc. under the Securities Exchange Act of 1934,
as amended, are under File No. 1-9187. Documents incorporated by reference to
filings made by IES Utilities Inc. under the Securities Exchange Act of 1934, as
amended, are under File No. 0-4117-1. Documents incorporated by reference to
filings made by Interstate Power Company under the Securities Exchange Act of
1934, as amended, are under File No. 1-3632.


                                      E-5