Background: Mathematics education is not often identified as the locus of radical social change work, with these topics assumed instead as fodder for social studies or language arts lessons. As such, teachers of mathematics can struggle to find avenues for their commitments to social and educational justice in their mathematics teaching spaces. Purpose: This study examined the practice and experiences of 10 math educators participating in a voluntary teacher learning community focused on critical pedagogies and math. The purpose was to identify the core learnings and challenges made possible through this learning community. Setting and Participants: The Critical Mathematics Teacher Collaborative (CMTC) consists primarily of preservice and early career K-12 teachers, all of whom teach math and seek to develop their own math teaching practices through frameworks of critical pedagogy and social justice. An informal, nonhierarchical learning community, CMTC uses a cycle of critical reflection and action: We read and discuss theory to inform visions for critical mathematics teaching, and we workshop participant-designed lesson plans to support moving from vision to action. Research Design: The study was collaboratively designed among members of the group as a self-study. Bidirectional interviews were conducted among 10 participants, transcribed, and analyzed. Conclusions: Four core insights were identified. Participating teachers (1) desired to be able to engage in critical work in mathematics teaching spaces, (2) were nurtured by accountability to a community that supports putting ideals into practice and continuing to examine these ideals, (3) benefitted from praxis--having a space to connect theory to the practices of daily classroom teaching, and (4) provided allyship to each other in the face of challenges to teaching for social justice, shaping not only their mathematics teaching but also teaching in spaces beyond mathematics. Examples of critical mathematics pedagogies in action in the classrooms of participating teachers are included, as well as appendices with readings and a sample agenda for use by teachers wishing to model a learning community of their own after this one.