Forest community-based social movements are today assuming increasingly important roles in environmental governance in the world's forests. As these "forest community stewards" promote local resource access and management, their organizations often take on greater internal complexity. This paper draws on the experience of the Association of Forest Communities of Petén (ACOFOP), Guatemala and the community-based concessions it serves to examine interactions among multiple forest activities, participants, interests and objectives in increasingly complex community-based organizations. Interntal interactions and tensions among multiple activities inevitably arise as these organizations seek to maintain their responsiveness and legitimacy amid rapidly changing social, political and environmental contexts. This paper suggests that rather than seek to eliminate tensions emerging from increased internal diversity and complexity, grassroots forest organizations should confront and manage these tensions to ensure continued viability while responding appropriately to moments of "structural choice". Seeing these community-based forest organizations as social movement processes managed over time by their participants rather than as sets of static principles best designed a priori allows more accurate analysis of the complex factors that shape success or failure, and of how appropriate external support may be provided.