This article examines the construction and experience of change agency within action research courses in preservice teacher education. Four preservice teachers' experiences of action research are analyzed, and tensions and challenges teacher educators and preservice teachers face as they attend to change processes in learning to teach are explored. This analysis suggests five central tensions in the process and pedagogy of action research: individual and institutional change, action and understanding, support and challenge, passion and reason, and regulation and emancipation. Rather than selecting one side of a tension over another, the authors argue that teacher educators need to work with tensions to develop understandings of change in relation to biography, teaching, and context. The authors argue that such contradictory and complex dimensions provide a useful frame for a pedagogy of action research. They are integral to the process of helping teacher candidates develop conceptions of teaching that embody change agency.