Purpose: Teachers unions in the United States are increasingly taking up issues of equity and justice. While there is a growing and robust body of scholarship on leading for equity, unions are rarely included as sources of education leadership. This creates an opportunity to not only consider unions in these equity efforts, but also re-shape our understandings of the shifting purposes and priorities of unions themselves. Methods: This paper synthesizes the literature to argue for the conceptualization of teachers unions as consequential sites of equity-focused leadership. Drawing from a larger year-long qualitative case study of a social-justice minded teachers union, I illustrate how a union may infrastructure towards equity by highlighting key mechanisms by which they lead. Findings & Implications: Through the creation of a union-based equity center and leveraging the collective bargaining agreement, this teachers union was able to implement formal structures to prioritize racial equity, educator agency, and autonomy. Unions are making strides to lead for equity and should be examined as a form of district leadership. Investigating these new contexts expands our conceptualizations of leadership and opens new possibilities for systemic change.