This excerpt taken from the PFG DEF 14A filed Apr 8, 2009.
How do I submit a shareholder proposal for the 2010 Annual Meeting?
The Company's next annual meeting is scheduled for May 18, 2010. In order to have a shareholder proposal considered for inclusion for the 2010 annual meeting, it must be received by December 10, 2009. In addition, a shareholder proposal may not be presented at the 2010 annual meeting and no one may be nominated for election to the Board by a shareholder at that meeting unless the Company receives notice of the proposal or nomination between January 19, 2010 and February 18, 2010. Proposals should be addressed to the Corporate Secretary. Your notice must comply with certain other requirements set forth in the Company's By-Laws, which are on the Company's website, www.principal.com, and may be obtained from the Corporate Secretary.