Participatory action research (PAR) with youth holds potential to spur social justice-oriented change due to its explicit orientation to transform systemic inequity. Whereas youth in PAR projects embody agency in their actions, they hold less institutional power than adults in positions of authority. In addition, youth who have been marginalized along lines of race, dis/ability, language, and/or other forms of socially constructed difference may be positioned in ways that further undermine their power. How PAR with youth can lead to changes in policies and practices in the face of these power dynamics is not yet fully understood. One mechanism that may heighten the potential of PAR with youth to promote change is a shared sense of responsibility and agency between the youth involved in PAR and those adults they may be trying to influence. This article explores this area, investigating a PAR project involving junior high youth at a K-8 school in an urban area. We examine the youth and school adults' constructions of responsibility and how these shaped possibilities for collective transformative agency. Ultimately, our article elucidates how PAR can more effectively be used as a lever to propel social justice in education.