In my copy of Baird's (from 1968, so a little outdated!), the NPC groups listed are:
Alpha Chi Omega
Alpha Delta Pi
Alpha Epsilon Phi
Alpha Gamma Delta
Alpha Omicron Pi
Alpha Phi
Alpha Sigma Alpha
Alpha Sigma Tau
Alpha Xi Delta
Chi Omega
Delta Delta Delta
Delta Gamma
Delta Phi Epsilon
Delta Zeta
Gamma Phi Beta
Iota Alpha Pi
Kappa Alpha Theta
Kappa Delta
Kappa Kappa Gamma
Phi Mu
Phi Sigma Sigma
Pi Beta Phi
Sigma Delta Tau
Sigma Kappa
Sigma Sigma Sigma
Theta Phi Alpha
Zeta Tau Alpha
If you can get your hands on a more current copy it'll tell you what happened to Iota Alpha Pi.
Lindsay
