Exhibit 5.01


                      [Letterhead of Debevoise & Plimpton]

December 19, 2003

Principal Financial Group, Inc.
711 High Street
Des Moines, Iowa  50392

                       The Principal Financial Group, Inc.
                       Registration Statement on Form S-3

Ladies and Gentlemen:

         We have acted as special counsel to Principal Financial Group, Inc.
(the "Company") in connection with the filing with the Securities and Exchange
Commission under the Securities Act of 1933, as amended (the "Act"), of a
Registration Statement on Form S-3 (the "Registration Statement"), relating to
the public offering by the Company of up to $3,000,000,000 in the aggregate of
(i) senior debt securities of the Company (the "Senior Debt Securities") to be
issued pursuant to an Indenture (the "Senior Indenture"), to be entered into
between the Company and The Bank of New York, as trustee (the "Senior Trustee"),
(ii) subordinated debt securities of the Company (the "Subordinated Debt
Securities" and together with the Senior Debt Securities, the "Debt Securities")
to be issued pursuant to a Subordinated Indenture (the "Subordinated Indenture"
and, together with the Senior Indenture, the "Indentures") to be entered into
between the Company and The Bank of New York, as trustee (the "Subordinated
Trustee"), (iii) junior subordinated debentures of the Company (the "Junior
Subordinated Debt Securities"), to be issued pursuant to a Junior Subordinated
Indenture (the "Junior Subordinated Indenture"), to be entered into between the
Company and Wilmington Trust Company, as trustee (the "Debenture Trustee"), (iv)
shares of preferred stock of the Company, par value $.01 per Share (the
"Preferred Stock"), (v) shares of Common Stock of the Company, par value $.01
per share (the "Common Stock"), (vi) depositary shares representing fractional
interests in Debt Securities or Preferred Stock (the "Depositary Shares"), (vii)
warrants representing rights to purchase Debt Securities, Preferred Stock or
Common Stock (the "Warrants") pursuant to one or more warrant agreements
("Warrant Agreements"), (viii) purchase contracts representing rights to
purchase Debt Securities, Preferred Stock, Common Stock, Depositary Shares,
Warrants, Preferred Securities (as defined below) or other property (the
"Purchase Contracts"), (ix) purchase units, representing ownership of Purchase
Contracts and Debt Securities (or undivided beneficial interests therein),
Depositary Shares, Preferred Securities (as defined below) or debt obligations
of third parties, including U.S. Treasury Securities (the "Purchase Units"), and
(x) preferred securities (the "Preferred Securities") of Principal Capital I,
Principal Capital II and Principal Capital III, each a statutory trust formed
under the laws of the State of Delaware (each, a "Trust" and collectively, the
"Trusts"), guaranteed to the extent the Trust has funds as set forth in the
Registration Statement by the Company (as such may be issued from time to time,
a "Guarantee" and, together with the Debt Securities, the Junior Subordinated
Debt Securities, the Preferred Stock, the Depositary Shares, the Common Stock,
the Warrants, the Purchase Contracts, the Purchase Units and




the Preferred Securities, the "Securities"), as well as up to an additional
$600,000,000 aggregate amount of such Securities that may be registered in
accordance with Rule 462(b) under the Act.

         In so acting, we have examined such corporate records, certificates and
other documents and such questions of law as we have considered necessary for
the purposes of this opinion.

Upon the basis of such examination, we are of the following opinion:

1.       When (i) the terms, and the execution and delivery, of the Senior
         Indenture have been duly authorized and approved by all necessary
         action of the Board of Directors of the Company or a duly authorized
         committee thereof (the "Board of Directors"), (ii) the Senior Indenture
         has been duly executed and delivered by the Company and the Senior
         Trustee, (iii) (a) the terms of the Senior Debt Securities and their
         issuance and sale have been duly authorized and approved by all
         necessary action of the Board of Directors and (b) the terms of the
         Senior Debt Securities have been duly established in accordance with
         the Senior Indenture and so as not to violate any applicable law, rule
         or regulation or result in a default under or breach of any agreement
         or instrument binding upon the Company and so as to comply with any
         requirement or restriction imposed by any court or governmental body
         having jurisdiction over the Company and (iv) the Senior Debt
         Securities have been duly executed, authenticated, issued and delivered
         as contemplated by the Registration Statement and any prospectus
         supplement relating thereto and in accordance with the Senior Indenture
         and any underwriting agreement, Warrants or Warrant Agreements relating
         to such issuance, against payment of the consideration fixed therefor
         by the Board of Directors, the Senior Debt Securities will be validly
         issued and will constitute valid and legally binding obligations of the
         Company enforceable against the Company in accordance with their terms.

2.       When (i) the terms, and the execution and delivery, of the Subordinated
         Indenture have been duly authorized and approved by all necessary
         action of the Board of Directors, (ii) the Subordinated Indenture has
         been duly executed and delivered by the Company and the Subordinated
         Trustee, (iii) (a) the terms of the Subordinated Debt Securities and
         their issuance and sale have been duly authorized and approved by all
         necessary action of the Board of Directors and (b) the terms of the
         Subordinated Debt Securities have been established in accordance with
         the Subordinated Indenture and so as not to violate any applicable law,
         rule or regulation or result in a default under or breach of any
         agreement or instrument binding upon the Company and so as to comply
         with any requirement or restriction imposed by any court or
         governmental body having jurisdiction over the Company and (iv) the
         Subordinated Debt Securities have been duly executed, authenticated,
         issued and delivered as contemplated by the Registration Statement and
         any prospectus supplement relating thereto and in accordance with the
         Subordinated Indenture and any underwriting agreement, Warrants or
         Warrant Agreements relating to such issuance, against payment of the
         consideration fixed

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         therefor by the Board of Directors, the Subordinated Debt Securities
         will be validly issued and will constitute valid and legally binding
         obligations of the Company enforceable against the Company in
         accordance with their terms.

3.       When (i) the terms, and the execution and delivery, of the Junior
         Subordinated Indenture have been duly authorized and approved by all
         necessary action of the Board of Directors, (ii) the Junior
         Subordinated Indenture has been duly executed and delivered by the
         Company and the Debenture Trustee, (iii) (a) the terms of the Junior
         Subordinated Debt Securities and their issuance and sale have been duly
         authorized and approved by all necessary action of the Board of
         Directors and (b) the terms of the Junior Subordinated Debt Securities
         have been established in accordance with the Junior Subordinated
         Indenture and so as not to violate any applicable law, rule or
         regulation or result in a default under or breach of any agreement or
         instrument binding upon the Company and so as to comply with any
         requirement or restriction imposed by any court or governmental body
         having jurisdiction over the Company and (iv) the Junior Subordinated
         Debt Securities have been duly executed, authenticated, issued and
         delivered as contemplated by the Registration Statement and any
         prospectus supplement relating thereto and in accordance with the
         Junior Subordinated Indenture and any underwriting agreement relating
         to such issuance, against payment of the consideration fixed therefor
         by the Board of Directors, the Junior Subordinated Debt Securities will
         be validly issued and will constitute valid and binding obligations of
         the Company enforceable against the Company in accordance with their
         terms.

4.       When (i) the terms of the Preferred Stock and of its issuance and sale
         have been duly established in conformity with the Company's Amended and
         Restated Certificate of Incorporation, as amended, and authorized and
         approved by all necessary action of the Board of Directors, so as not
         to violate any applicable law, rule or regulation or result in a
         default under or breach of any agreement or instrument binding upon the
         Company and so as to comply with any requirement or restriction imposed
         by any court or governmental body having jurisdiction over the Company,
         (ii) a Certificate of Designation fixing and determining the terms of
         the Preferred Stock has been duly filed with the Secretary of State of
         the State of Delaware and (iii) certificates for the shares of the
         Preferred Stock have been duly executed, authenticated, issued and
         delivered as contemplated by the Registration Statement and any
         prospectus supplement relating thereto and in accordance with any
         underwriting agreement, Warrants or Warrant Agreements or Purchase
         Contracts relating to such issuance, against payment of the
         consideration fixed therefor by the Board of Directors, the Preferred
         Stock will be duly authorized, validly issued, fully paid and
         nonassessable.

5.       When (i) the terms, and the execution and delivery, of the Deposit
         agreement or Agreements relating to the Depositary Shares and the terms
         of the Depositary Shares and of their issuance and sale have been duly
         authorized and approved by all necessary action of the Board of
         Directors, (ii) the Depositary Agreement or Agreements relating to the
         Depositary Shares and the depositary receipts evidencing the Depositary
         Shares (the "Depositary Receipts") have been duly

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         authorized, executed and delivered by the Company and such depositary
         as shall have been duly appointed by the Company (the "Depositary"),
         (iii) the terms of the Depositary Shares and the Depositary Receipts
         have been established in accordance with the applicable Deposit
         Agreement so as not to violate any applicable law, rule or regulation
         or result in a default under or breach of any agreement or instrument
         binding upon the Company, and so as to comply with any applicable
         requirement or restriction imposed by any court or governmental
         authority having jurisdiction over the Company, (iv) (a) (1) the
         Indentures have been duly authorized, executed and delivered by the
         Company and the Senior Trustee or the Subordinated Trustee, as the case
         may be, as contemplated in paragraph 1 or 2 above, as the case may be,
         and (2) the Debt Securities relating to the Depositary Shares have been
         duly authorized, executed, authenticated, issued and delivered as
         contemplated in paragraph 1 or 2 above, as the case may be, or (b) the
         shares of Preferred Stock relating to the Depositary Shares have been
         duly authorized and validly issued and are fully paid and
         non-assessable as contemplated in paragraph 4 above and, in the case of
         either (a) or (b), have been deposited with the Depositary under the
         applicable Deposit Agreement, and (v) the Depositary Receipts have been
         duly executed, countersigned, registered and delivered, as contemplated
         by the Registration Statement and any prospectus supplement related
         thereto, and in accordance with the terms of the Deposit Agreement and
         any underwriting agreement relating to such issuance, against payment
         of the consideration fixed therefor by the Board of Directors, the
         Depositary Receipts will be validly issued and will entitle the holders
         thereof to the rights specified therein and in the Deposit Agreement.

6.       When (i) the terms of the issuance and sale of the Common Stock have
         been duly authorized and approved by all necessary action of the Board
         of Directors so as not to violate any applicable law, rule or
         regulation or result in a default under or a breach of any agreement or
         instrument binding upon the Company and so as to comply with any
         requirement or restriction imposed by any court or governmental body
         having jurisdiction over the Company and (ii) certificates for the
         shares of Common Stock have been duly executed, authenticated, issued
         and delivered as contemplated by the Registration Statement and any
         prospectus supplement relating thereto, and in accordance with any
         underwriting agreement, Warrants or Warrant Agreements or Purchase
         Contracts relating to such issuance, against payment of the
         consideration fixed therefor by the Board of Directors, the Common
         Stock will be duly authorized, validly issued, fully paid and
         nonassessable.

7.       When (i) the terms, and the execution and delivery, of the Warrants and
         any Warrant Agreement or Agreements relating to the Warrants and the
         terms of the issuance and sale of the Warrants and related matters have
         been duly authorized and approved by all necessary action of the Board
         of Directors, (ii) the Warrant Agreement or Agreements relating to the
         Warrants have been duly executed and delivered by the Company and such
         warrant agent as shall have been duly appointed by the Company, (iii)
         the terms of the Warrants have been established in accordance with the
         applicable Warrant Agreement and so as not to violate any

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         applicable law, rule or regulation or result in a default under or a
         breach of any agreement or instrument binding upon the Company and so
         as to comply with any requirement or restriction imposed by any court
         or governmental body having jurisdiction over the Company and (iv) the
         Warrants or certificates representing the Warrants have been duly
         executed, authenticated, issued and delivered as contemplated by the
         Registration Statement and any prospectus supplement relating thereto,
         and in accordance with the terms of any Warrant Agreement and
         underwriting agreement relating to such issuance, against payment of
         the consideration fixed therefor by the Board of Directors, the
         Warrants will constitute valid and legally binding obligations of the
         Company enforceable against the Company in accordance with their terms.

8.       When (i) the terms, and the execution and delivery, of the Purchase
         Contracts and the terms of the issuance and sale thereof and related
         matters have been duly authorized and approved by all necessary action
         of the Board of Directors, (ii) the terms of the Purchase Contracts
         have been established so as not to violate any applicable law, rule or
         regulation or result in a default under or a breach of any agreement or
         instrument binding upon the Company and so as to comply with any
         requirement or restriction imposed by any court or governmental body
         having jurisdiction over the Company and (iii) the Purchase Contracts
         have been duly executed and delivered by the Company and such contract
         agent as shall have been duly appointed by the Company and any
         certificates representing Purchase Contracts have been duly executed,
         authenticated, if required, issued and delivered, in each case, as
         contemplated by the Registration Statement and any prospectus
         supplement relating thereto, and in accordance with any Purchase
         Contract and underwriting agreement related to such issuance, against
         payment of the consideration fixed therefor by the Board of Directors,
         the Purchase Contracts will constitute valid and legally binding
         obligations of the Company enforceable against the Company in
         accordance with their terms.

9.       When (i) the terms of the Purchase Units and the terms of the issuance
         and sale thereof and related matters have been duly authorized and
         approved by all necessary action of the Board of Directors, (ii) the
         terms of the Purchase Units have been established so as not to violate
         any applicable law, rule or regulation or result in a default under or
         a breach of any agreement or instrument binding upon the Company and so
         as to comply with any requirement or restriction imposed by any court
         or governmental body having jurisdiction over the Company, (iii) the
         Purchase Contracts that form a part of the Purchase Units have been
         duly authorized, executed, authenticated (if required), issued and
         delivered as contemplated in paragraph 8 above, (iv) (a) (1) the
         Indenture relating to the Debt Securities (or undivided beneficial
         interests therein) that form a part of the Purchase Units or that are
         deposited under the Deposit Agreement referred to below has been duly
         authorized, executed and delivered by the Company and the Senior
         Trustee or the Subordinated Trustee, as the case may be, as
         contemplated in paragraph 1 or 2 above, as the case may be, and (2) the
         Debt Securities (or undivided beneficial interests therein) that form a
         part of the Purchase Units or that have been deposited under the
         Deposit Agreement referred to below have

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         been duly authorized, executed, authenticated, issued and delivered as
         contemplated in paragraph 1 or 2 above, as the case may be, (b) the
         Preferred Stock that form a part of the Purchase Units have been duly
         authorized, executed, authenticated, issued and delivered as
         contemplated in paragraph 4 above, (c) (1) the Depositary Agreement or
         Agreements relating to the Depositary Shares that form a part of the
         Purchase Units, the related Depositary Shares and the Depositary
         Receipts evidencing such Depositary Shares have been duly authorized,
         executed, authenticated, if required, and delivered as contemplated by
         paragraph 5 above and (3) either (A) the Indentures have been duly
         authorized, executed and delivered by the Senior Trustee or the
         Subordinated Trustee, as the case may be, as contemplated in paragraph
         1 or 2 above, as the case may be, and the Debt Securities relating to
         the Depositary Shares that form a part of the Purchase Units have been
         duly authorized, executed, authenticated, issued and delivered as
         contemplated in paragraph 1 or 2 above, as the case may be, (d) the
         debt obligations, including U.S. Treasury Securities, of third parties
         that form a part of the Purchase Units have been duly authorized,
         issued and delivered in accordance with their terms or (e) the
         preferred securities of the Trusts that form part of the Purchase Units
         have been duly authorized, issued and delivered in accordance with
         their terms, and (v) the certificates representing the Purchase Units
         have been duly executed, authenticated, if required, issued and
         delivered as contemplated by the Registration Statement and any
         prospectus supplement relating thereto, and in accordance with any
         Purchase Contract and underwriting agreement relating to such issuance,
         against payment of the consideration fixed therefor by the Board of
         Directors, the Purchase Units will be duly authorized and validly
         issued.

10.      When (i) a Guarantee has been duly authorized and approved by the Board
         of Directors and (ii) such Guarantee has been validly executed and
         delivered by the Company, such Guarantee will constitute a valid and
         legally binding obligation of the Company enforceable against the
         Company in accordance with its terms.

11.      If the Debt Securities are exchangeable or convertible into Common
         Stock, when (i) the terms of the issuance of the Common Stock have been
         duly authorized and approved by all necessary action of the Board of
         Directors, and (ii) the shares of Common Stock have been issued in
         exchange for or upon conversion of such Debt Securities as contemplated
         by the Registration Statement and any prospectus supplement relating
         thereto, in accordance with the terms of the Debt Securities and the
         applicable Senior Indenture or Subordinated Indenture, as the case may
         be, so as not to violate any applicable law, rule or regulation or
         result in a default under or a violation of any agreement or instrument
         binding upon the Company, and so as to comply with any applicable
         requirement or restriction imposed by any court or governmental
         authority having jurisdiction over the Company, the shares of Common
         Stock so issued will be duly authorized, validly issued, fully paid and
         non-assessable.

         The opinions set forth above are subject to the following additional
         qualifications:


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         (a) Our opinions in paragraphs 1, 2, 3, 7, 8 and 10 above are subject
to the effects of (i) bankruptcy, insolvency, fraudulent conveyance, fraudulent
transfer, reorganization, moratorium or other similar laws relating to or
affecting enforcement of creditors' rights or remedies generally, (ii) general
principles of equity, whether such principles are considered in a proceeding of
law or in equity, and (iii) an implied covenant of good faith, reasonableness
and fair dealing, and standards of materiality.

         (b) With respect to the opinions set forth in paragraphs 1 through 11,
we express no opinion as to (1) any waiver of inconvenient forum set forth in
any agreement or (2) any provision relating to judgments in currencies other
than United States dollars. We express no opinion concerning whether a United
States Federal court would accept jurisdiction in any dispute, action, suit or
proceeding arising out of or relating to any agreement or the transactions
contemplated thereby.

         (c) The opinions expressed in paragraphs 1 through 11 above are limited
to the laws of the State of New York and the General Corporation Law of the
State of Delaware, including the applicable provisions of the Delaware
Constitution and the reported cases interpreting those laws.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to our firm under the heading "Legal
Opinions" in the Prospectus forming a part thereof and to the incorporation by
reference of this opinion and consent as exhibits to any registration statement
filed in accordance with Rule 462(b) under the Act relating to the Securities.
In giving such consent, we do not thereby admit that we are in the category of
persons whose consent is required under Section 7 of the Act.

                                                     Very truly yours,

                                                     /s/ Debevoise & Plimpton

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