SecProbe.io

June 29, 2010
 Terrance J. Lillis Senior Vice President and Chief Financial Officer Principal Financial Group, Inc. 711 High Street Des Moines, Iowa 50392
Re: Principal Financial Group, Inc.
 Form 10-K for the Fiscal Year Ended December 31, 2009
Form 10-Q for the Quarterly Period Ended March 31, 2010 File No. 001-16725

Dear Mr. Lillis:
 We have limited our review of your filings to  those issues we have addressed in our
comments.  In some of our comments, we may ask you to provide us with information so we may better understand your disclosure.
 Please respond to this letter within te n business days by providing the requested
information, or by advising us when you will provide the requested response.  Where a comment requests you to revise disclosu re, the information you provide s hould show us what the revised
disclosure will look like and identify the annual or quarterly filing, as applicable, in which you
intend to first include it.  If you do not be lieve our comments apply to your facts and
circumstances, please tell us why in your res ponse.  Please furnish us a letter on EDGAR under
the form type label CORRESP that ke ys your responses to our comments.
 After reviewing the information you provide in response to these comments, we may
have additional comments and/or request that you amend your filing     Form 10-K for the fiscal year ended December 31, 2009

Notes to the Consolidated Financial Statements
5. Investments, page 106
 1. Your disclosure does not appear to comply  fully with note 6 to Article 7-03.1 of
Regulation S-X.  Please revise  to disclose the name and aggregate amount invested in
each person and its affiliates that exceed s 10% of your total stockholders’ equity.
 Commercial Mortgage Loans, page 112

 2. Please disclose, preferably in a table, loans in your commercial lo an portfolio grouped by
current loan-to-value ratio, as appropriate, to provide informative disclosure about the

Terrance J. Lillis Principal Financial Group, Inc. June 29, 2010 Page 2

risks in your portfolio. For example, groupings  could include loans classified as low,
medium or high loan-to-value ratio with a not e explaining the definiti on of low, medium
and high.
 Form 10-Q for the quarterly period ended March 31, 2010

 Notes to the Consolidated Financial Statements

9. Fair Value Measurements, page 34
 3. Please revise your disclosures for assets and liabilities classified as  Level 2 and Level 3
to quantify the inputs used in determining th e fair value of each class of assets or
liabilities as required by AS C 820-10-50-2e as amended by ASU 2010-06.  Please see
ASC 820-10-55-22A for examples of  the inputs to  be disclosed.

We urge all persons who are responsible for th e accuracy and adequacy of the disclosure
in the filings to be certain that the filings incl ude the information the Secu rities Exchange Act of
1934 and all applicable Exchange Act rules requir e.  Since the company and its management are
in possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of the disclosures they have made.
 In responding to our comments, please provi de a written statement from the company
acknowledging that:
• the company is responsible for the adequacy an d accuracy of the disclo sure in the filings;
• staff comments or changes to disclosure in response to staff comments do not foreclose
the Commission from taking any action with respect to the filings; and
• the company may not assert staff comments as  a defense in any proceeding initiated by
the Commission or any person under the federa l securities laws of  the United States.

You may contact Vanessa Robert son, Staff Accountant, at (202) 551-3649 or Mary Mast,
Senior Staff Accountant, at ( 202) 551-3613 if you have any questi ons regarding the comments.
In this regard, do not hesitate  to contact me, at (202) 551- 3679 with any other questions.

Sincerely,

Jim B. Rosenberg Senior Assistant Chief Accountant