[AlphaSigOU]

Phi Pi Phi was founded in 1915 in Chicago, and merged with Alpha Sigma Phi in 1938. There were some chapter overlaps, and active members in Phi Pi Phi were automatically granted membership in Alpha Sigma Phi. Members from dormant chapters where no chapter of Alpha Sigma Phi exists may request initiation as a member-at-large (without specific chapter affiliation).

Alpha Kappa Pi was founded in 1926 at Wagner College, when a local fraternity at Newark College of Engineering (now New Jersey Institute of Technology) and another local fraternity at Wagner College combined to form Alpha Kappa Pi. On September 6, 1945, Alpha Kappa Pi consolidated with Alpha Sigma Phi.

Unlike the merger with Phi Pi Phi in 1939, the consolidation with Alpha Kappa Pi brought about many changes to Alpha Sigma Phi. The constitution, bylaws and ritual were changed, and the Alpha Kappa Pi Badge became the Pledge Pin of the Fraternity The Sister Pin of Alpha Kappa Pi was adopted as the official sister pin by replacing the Greek letters Alpha Kappa Pi with Alpha Sigma Phi.. All chapters of Alpha Kappa Pi were added, including a considerable number that were never reactivated after World War II.

In 1965, Alpha Gamma Upsilon Fraternity partially merged with Alpha Sigma Phi. Alpha Gamma Upsilon was founded at Anthony Wayne Institute in Fort Wayne, Indiana, in 1922, the merger adding five new chapters to 'The Old Gal'. The remaining chapters of Alpha Gamma Upsilon that chose not to merge with Alpha Sigma Phi were later merged with other fraternities.