The NPC webpage (
www.npcwomen.org) has very clear guidelines how to go about the expansion process.
In a nutshell, your local panhellenic must vote to invite a group to colonize on your campus. The local chapter who is seeking national affiliation can start by sending a letter of inquiry to the groups they are most interested in joining. Yes, those groups will want all sorts of statistics before they'll even agree to make a presentation. Rush numbers, enrollment figures, and academic data is a start.
Hope this helps.. I wish you luck!
Karen Gunther
Pi Beta Phi
Director of Academics