Collaborations between education stakeholders are increasingly prevalent due to the need for diverse perspectives on issues of justice in education. Less is known, however, about how stakeholders form heterogeneous communities where people from different backgrounds learn and take action together. This study examined the contours of a community that emerged from a three-year partnership between mathematics teachers, community educators, and university scholars. This racially- and gender-diverse community was marked by contention and affirmation, which illuminates the complex and politicized nature of the joint work. This study illuminates tensions across dimensions of the community including spaces as affirming and fraught, goals as shared and contested, belonging as ebbing and flowing, relationships as personal and political, and roles as imposed and amorphous.