Phi Sigma Alpha Fraternity (ΦΣΑ) ( Fi Sigma Alfa) commonly known as La Sigma, is a Puerto Rican fraternity established originally 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. as well as to the first ever Greek letter Hispanic-oriented fraternity Sigma Iota established in 1912.
Phi Sigma Alpha traces its origins to a number of organizations including Phi Lamba Alpha. Phi Lambda Alpha fraternity was founded at the University of California, at Berkeley in 1919. The fraternity was a merger of three societies; the Unión Hispano Americana at Rensselaer Polytechnic Institute, Troy, New York founded in 1898, the first Latin-American student society in the USA; A group of Latin American students organized the Union Hispano Americana (UHΑ) as a cultural and intellectual secret society based on the ideology of Pan-Americanism.