Ontario Secondary School Teachers Federation

Ontario Secondary School Teachers Federation (OSSTF) is a trade union that represents secondary school teachers, occasional teachers and other education workers employed in Ontario’s publicly funded school system. Its primary function is to negotiate collective agreements with school boards on behalf of its members, covering wages, working conditions and benefits. In addition to bargaining, OSSTF offers various services to support its members, such as legal assistance and professional development resources. The federation also engages in advocacy efforts aimed at influencing provincial education policy and funding decisions. OSSTF produces research and communications to inform members about relevant issues in the education sector. The organization operates democratically, with elected leaders and local branches that enable member participation.

Headquartered in Canada, OSSTF carries out its activities primarily within the province of Ontario, reflecting its sector‑specific focus on secondary education. This concentration allows the federation to develop specialized knowledge of issues relevant to secondary education. While the exact size of its membership is not disclosed in the provided sources, OSSTF is a significant union representing education professionals in Ontario. Structurally, it is an independent federation that functions within the broader Canadian labour movement. A notable event in its recent history occurred on May 30, 2022, when the federation suffered a ransomware attack that compromised sensitive personal information of its members, prompting notification, investigation and mitigation efforts. This incident highlighted the importance of cybersecurity protections for organizations that manage extensive member data.