It was formally organized on November 19, 1920, in a meeting held at the Metropolitan Restaurant in Intramuros, Manila where the fraternity elected its first officers (among which include Agapito del Rosario, one of the founders of the Socialist Party of the Philippines and later on Mayor of Angeles, Pampanga).

[3][4][5] Four months later, on March 24, 1921, the Greek letters "ΥΣΦ", standing for the initials of the name "University Students Fraternity" were formally adopted.

[6] From 1930 to 1949, then UP Student Council President Wenceslao Vinzons, together with members of the fraternity, led demonstrations before the Philippine Congress to protest the insertion of a provision in the appropriations act that gave lawmakers a salary increase.

Through the efforts of the UP Alumni Association headed by Upsilonian Hermenegildo Reyes, the fraternity helped raise funds for the construction of the bell tower called the "Carillon".

[22] Membership in Upsilon Sigma Phi is by invitation only and is exclusive to male students at the University of the Philippines Diliman, Manila, and Los Baños campuses.

[39] Philippine President Ramon Magsaysay assigned an ad hoc medico-legal committee, that failed to indicate that hazing "contributed to Albert's death" in their findings; albeit which jeopardized his physical condition before the patient's appendectomy.

[40][41] The committee further recommended the expulsion of four officers of the fraternity, implicated residents and neophytes being suspended, and a censure of several UP deans, directors, and faculty members for their collective remiss to discharge proactive duties.

[52] The incident prompted campus authorities to tighten security within the UP system and a statement of condemnation from Diliman chancellor Tan and UP president Concepcion.

[53][54] The same month, a Facebook Messenger chat by alleged Upsilon members was penetrated by a rival frat[55][56][57][58] to reveal misogynous banter censured by UP President Danilo Concepcion, himself an Upsilonian, as "reprehensible and totally unacceptable" language by its fellows.