There are 3 NPC's that begin with Sigma
Sigma Kappa
Sigma Sigma Sigma
Sigma Delta Tau
One NPHC
Sigma Gamma Rho Sorority, Inc.
Nine NIC fraternities:
Sigma Alpha Epsilon
Sigma Alpha Mu
Sigma Chi
Sigma Lambda Beta
Sigma Nu
Sigma Phi Epsilon
Sigma Phi Society
Sigma Pi
Sigma Tau Gamma
And three NALFO members
Sigma Lambda Gamma Sorority, Inc.
Sigma Lambda Upsilon/Seņoritas Latinas Unidas Sorority, Inc.
Sigma Delta Alpha Fraternity, Inc.