Alpha Sigma Phi is an international intercollegiate men's social fraternity that was established at Yale University in 1845. It absorbed 4 chapters of Phi Phi Phi in 1939, followed by 28 active chapters of Alpha Kappa Pi on September 6, 1946. In 1965, it absorbed Alpha Gamma Upsilon. The fraternity refers to colonies as provisional chapters.
In the following list of Alpha Sigma Phi chapters, active chapters are in bold and inactive chapters and institutions are in italics.