Teachers' unions and community organizing emerged out of shared collective struggles for social justice in the United States in the twentieth century. Beyond broad general aspirations for a better society, however, their interests and tactics have not always been compatible. This interpretive essay revisits three recent case studies of interaction between teachers and community organizing groups to investigate the conditions that can lead to episodic tactical relationships, entrenched polarization, or solidarity. The cases indicate that while there are many potential causes of mistrust between teachers and community activists, concrete and practical strategies can be forged that can improve student learning, benefit teachers collectively, and increase community engagement in public schools.