Organizations within challenger movements often exhibit differences in what they do, with whom they interact, and how they understand or present themselves. This article attempts to understand what underlies such heterogeneity in challenger movements. Adopting a mixed method approach, we explore the heterogeneous nature of the work undertaken by institutional challengers in the US environmental movement. Drawing on the tools of social network analysis, we develop a method to identify a set of distinct social positions. Next, drawing upon qualitative data on identity and work from websites and interviews with senior managers in environmental non-governmental organizations, we identify configurations of social position, identity, and work that result in a distinct set of challenger roles. Our analysis reveals how identity and social position can both enable and constrain individual organizations within a challenger movement in terms of their ability to undertake different types of institutional work. We also identify a form of work thus far not explicitly identified in prior studies of institutional work–indirect work, which we theorize may be an important potential moderator to the effectiveness of direct forms of institutional work.