From the 2002 Beta Theta Pi Pledge Manual
Son of the Stars
Organization (#of chapters) Initiates
Alpha Phi Alpha (259) 75,250
Iota Phi Theta (147) 18,000
Kappa Alpha Psi (326) 80,000
Omega Psi Phi (194) 100,000
Phi Beta Sigma (371) 90,000
Alpha Kappa Alpha (330) 113,000
Delta Sigma Theta (292) 85,000
Sigma Gamma Rho (172) 71,000
Zeta Phi Beta (85) 113,000
I don't know the accuracy of these. I'm not sure if the chapter numbers are only collegiate chapters or all chapters. I figure these are probably decent estimates. I strongly suggest that EVERYONE ON GREEKCHAT bookmark
Ariesrising's Greek Info Pages as she has everything most people ask for...# of chapters, pictures of badges and pledge pins, and other information.
NOTE to Moderators or John...Would it be possible to create a new forum for "Greek Facts" with just a link to that page??? I think it would help everyone out a lot.