Phi Sigma Alpha (ΦΣΑ), commonly known as La Sigma, is a Puerto Rican fraternity originally established as the Sigma Delta Alpha Fraternity on October 22, 1928, at the University of Puerto Rico by twelve 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.

The University of Puerto Rico, Río Piedras Campus is a public land-grant research university in San Juan, Puerto Rico. It is the largest campus in the University of Puerto Rico system in terms of student population and it was Puerto Rico's first public university campus.