Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Prospectus Date	rr_ProspectusDate	Feb. 29, 2012
SmallCap Value Fund II (Prospectus Summary): \| SmallCap Value Fund II
Risk/Return:	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	SMALLCAP VALUE FUND II
Supplement Text	ck0000898745_SupplementTextBlock	Supplement dated April 20, 2012 to the Class J Shares Prospectus for Principal Funds, Inc. dated February 29, 2012 (as supplemented on March 16, 2012) This supplement updates information currently in the Prospectus. Retain this supplement with the Prospectus. FUND SUMMARIES SMALLCAP VALUE FUND II Under the Annual Fund Operating Expenses table, delete the fourth footnote and substitute: (4) Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund’s expenses attributable to Class J 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 1.926%. 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.
SmallCap Value Fund II \| Class J
Risk/Return:	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	PSMJX

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Prospectus Date

rr_ProspectusDate

Feb. 29, 2012

SmallCap Value Fund II (Prospectus Summary): | SmallCap Value Fund II

Risk/Return:

rr_RiskReturnAbstract

Risk/Return, Heading

rr_RiskReturnHeading

SMALLCAP VALUE FUND II

Supplement Text

ck0000898745_SupplementTextBlock

Supplement dated April 20, 2012

to the Class J Shares Prospectus

for Principal Funds, Inc.

dated February 29, 2012

(as supplemented on March 16, 2012)

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

FUND SUMMARIES

SMALLCAP VALUE FUND II

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

(4) Principal Management Corporation ("Principal"), the investment advisor, has contractually agreed to limit the Fund’s expenses attributable to Class J 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 1.926%. 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.

SmallCap Value Fund II | Class J

Risk/Return:

rr_RiskReturnAbstract

Trading Symbol

dei_TradingSymbol

PSMJX