UPSILON PHI SIGMA (YΦΣ, commonly known as UPS) is a National Inter-University and Collegiate Fraternity and Sorority with 164 active chapters. Founded at the University of the Philippines Los Baños in February 14, 1935, it is one of the oldest fraternities and sororities in the Philippines.

The organization practices many traditions. The most important of these traditions is the giving of 100 red roses every Valentine's Day during the Founding Anniversary. This is guided by the Latin motto, Unitas, Pax, Et Salus! ("Unity, Peace, and Prosperity for All!"). The organization's official symbol is the shield, signifying the strong establishment of the organization in the early 1900s. Due to the active expansion efforts of the members, Upsilon Phi Sigma continues to offer humanitarian services to the schools and communities of the Philippines.