Phi Sigma Alpha (ΦΣΑ), commonly known as La Sigma, is a Puerto Rican fraternity originally established as the Sigma Delta Alpha Fraternity (Sociedad de Amigos) on October 22, 1928, at the University of Puerto Rico by 12 students and a professor. Phi Sigma Alpha can trace its roots back to 1898 to the Union Hispano Americana, as well as to the first ever Greek letter Hispanic-oriented fraternity, Sigma Iota, established in 1912. By 1998 there were over 4,376 members.