Historically teachers’ federations have been some of the major organizational sites for social justice leadership in K-12 public education. Despite this history of activism, social justice teacher unionism remains a relatively underdeveloped concept. This article merges four philosophical conceptions of social justice in education: liberal recognition, critical recognition, liberal distribution, and critical distribution, with an analysis of equity-based initiatives articulated on the Web sites of 20 Canadian teach- ers’ organizations. The resulting framework can be used by teacher union researchers interested in generating a broader conception of social justice unionism, and teacher unionists interested in investigating their organizational practices through a social justice lens.