Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Prospectus Date

rr_ProspectusDate

Feb. 29, 2012

LargeCap Value Fund (Prospectus Summary): | LargeCap Value Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return, Heading

rr_RiskReturnHeading

LARGECAP VALUE FUND  

Supplement Text

ck0000898745_SupplementTextBlock

Supplement dated April 20, 2012

to the Class A, Class B, Class C, and Class P Shares Prospectus

for Principal Funds, Inc.

dated February 29, 2012

(as supplemented on March 16, 2012, March 29, 2012, and April 9, 2012)

This supplement updates information currently in the Prospectus. Retain this supplement with the Prospectus.

FUND SUMMARIES

LARGECAP VALUE FUND

Under the Annual Fund Operating Expenses table, delete the footnote and substitute:

 (1)  Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund’s expenses attributable to Class B and Class C shares and, if necessary, pay expenses normally payable by the Fund, excluding interest expense and Acquired Fund Fees and Expenses, through the period ending February 28, 2013. The expense limit will maintain a total level of operating expenses (expressed as a percent of average net assets on an annualized basis) not to exceed 2.00% for Class B and 1.70% for Class C. It is expected that the expense limit will continue through the period disclosed; however, Principal Funds, Inc. and Principal, the parties to the agreement, may agree to terminate the expense limit prior to the end of the period.

LargeCap Value Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Trading Symbol

dei_TradingSymbol

PCACX

LargeCap Value Fund | Class B

Risk/Return:

rr_RiskReturnAbstract

Trading Symbol

dei_TradingSymbol

PCCBX

LargeCap Value Fund | Class C

Risk/Return:

rr_RiskReturnAbstract

Trading Symbol

dei_TradingSymbol

PLUCX