Sustainable tourism research has generated substantial insights into environmental, social, economic, governance, and cultural dimensions of sustainability. However, existing approaches provide limited explanation of how different capacities interact through stewardship processes to shape divergent sustainability trajectories under conditions of uncertainty and change. This paper develops the Adaptive Socio-Ecological Stewardship Framework (ASES) to conceptualize sustainable tourism as an adaptive process emerging from interactions among interconnected stewardship capacities within complex socio-ecological systems. Drawing on interdisciplinary scholarship from sustainable tourism, socio-ecological systems, adaptive governance, resilience theory, sustainability transitions, and community development, the paper synthesizes existing knowledge into an integrated conceptual framework. ASES identifies five stewardship capacities: community agency, institutional capacity, technological capacity, ecological capacity, and cultural capacity. Rather than treating these capacities as separate sustainability dimensions, ASES explains how their reinforcing, constraining, and conditional interactions generate alternative sustainability pathways. The framework proposes four adaptive stewardship configurations: regenerative sustainability, technocratic sustainability, fragile sustainability, and unsustainable lock-in. By shifting analytical attention from sustainability pillars toward the mechanisms through which stewardship capacities interact, ASES contributes a tourism-specific framework for understanding adaptation, transformation, and sustainability transitions. The framework provides a foundation for future empirical testing, adaptive governance, and regenerative tourism planning.