The initial catalyst for the creation of OUSA was disagreement over the position of the provincial and national student association in Ontario on the first Gulf War. In 1992, The student associations of
Brock University,
Queen's University, the
University of Waterloo and
Wilfrid Laurier University, and the Association of Part-Time Undergraduate Students at the
University of Toronto approached the
Ontario Federation of Students(OFS) to host a roundtable discussing the prospect of pushing for an increase in tuition fees. When this idea was rejected, the roundtable occurred informally and resulted in the formal incorporation and creation of OUSA. In May 2013, the
University of Windsor Students' Alliance voted, through a referendum, to leave the Alliance. On April 29, 2014, the
McMaster Association of Part-Time Students also withdrew from membership in OUSA. The
Students' General Association (SGA-AGÉ) of
Laurentian University was admitted into OUSA in April 2016, with membership taking effect May 2016. Most recently, the
Ontario Tech Student Union (OTSU) joined OUSA as a full member in April 2023. ==Members==