Tau Beta Sigma Honorary Band Sorority, (ΤΒΣ, colloquially referred to as TBSigma or TBS) is a co-educational service sorority. The sorority, headquartered at the historic Stillwater Santa Fe Depot in Stillwater, Oklahoma, numbers over 3,800 active members in 160 active chapters, and over 40,000 alumni. Since 1946, Tau Beta Sigma has been recognized by Kappa Kappa Psi as "an equal affiliated organization with a parallel purpose, function and role in the college and university band setting", and the two organizations hold joint conventions. The two organizations contribute to a national publication called, The Podium. Tau Beta Sigma also administers an alumni association open to members and friends of both organizations.