Definitive Materials Filed by Investment Companies. (497)

April 2, 2014

Securities and Exchange Commission

Via EDGAR

Re:    Principal Funds, Inc.

File Nos. 033-59474, 811-07572

Interactive data files for previous 497 filing

Principal Funds, Inc. (“the Registrant”) is incorporating by reference the supplement filed on March 14, 2014 (SEC Accession No. 0000898745-14-000476).

Pursuant to Rule 497 under the Securities Act of 1933, as amended, the Registrant is filing interactive data files that relate to Form N-1A items 2-4 in the supplement that the Registrant is incorporating by reference.

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Exhibit No.      Exhibits

Ex-101.INS      XBRL Instance Document

Ex-101.SCH      XBRL Taxonomy Extension Schema Document

Ex-101.CAL      XBRL Taxonomy Extension Calculations Linkbase Document

Ex-101.DEF      XBRL Taxonomy Extension Definition Linkbase Document

Ex-101.LAB      XBRL Taxonomy Extension Labels Linkbase Document

Ex-101.PRE      XBRL Taxonomy Extension Presentation Linkbase Document