Teacher attrition and teacher burnout are among the most serious problems facing urban schools today. With teachers under constant siege, under resourced, and often under prepared, the revolving door of urban teaching has left schools, and therefore children, in a constant state of flux. These dehumanizing and de-intellectualized conditions of teaching have led many would-be critical educators out of the classroom. Without stable teaching forces in central city schools, students and staffs are at a loss to build networks of trust or engage in long-term, local-level reforms. The recent emphasis on teacher education is important, but it cannot overshadow the need to focus on the teachers who are already in schools. Key components in the struggle for social justice urban schools have to be teacher retention and meaningful professional development. This article examines a critical research seminar involving urban students and teachers as a site for teacher learning and development. The author locates this work within critical and sociocultural traditions to advocate for professional development that is situated in meaningful practice and empowering of teachers as intellectuals and as agents of reform. He describes in detail the summer research seminar of the Institute for Democracy, Education, and Access (IDEA), a community of practice where urban students and teachers, along with university researchers, come together to investigate issues related to equity and access for marginalized populations within schools. From a variety of sources, including interview and survey data, videotapes of seminar activity, and transcripts from meetings, the author articulates four key participation structures that facilitated legitimate peripheral participation during the critical research seminar. He concludes by suggesting ways that learning generated from this seminar can assist teachers, administrators, and teacher-educators who wish to reconsider professional development.