Transboundary Spanning in Social Movements: Organizational Structure and Antiracism in the US Extinction Rebellion Movement

ABSTRACT This paper introduces transboundary spanning as a novel concept for social movement analysis. Using Extinction Rebellion (XR) in the United States as a case study, we examine the relational dynamics of social movement boundary spanning: processes wherein actors and organizations engage across symbolic boundaries. Drawing on a 3‐month ethnography of XR in the Northeastern US, 44 in‐depth semi‐structured interviews with US activists, and 199 interviews across 24 other countries, we examine how divisions over racial justice and organizational configuration played out within the movement. Our analysis illustrates how social movement transboundary spanning works in practice, interrogating the ways in which multiple forms of boundary spanning occur simultaneously, impacting each other and creating multiplex outcomes. The study contributes to key debates in sociology by providing a granular analysis of how the politics of race and organizational debates unfold at the meso level of environmental social movement organizations.