Wild animals around the world are profoundly impacted by tourism activities, much of which endangers their lives. This paper builds on growing scholarship demonstrating how wildlife sanctuaries can advance animal welfare and species conservation–– prerequisites for truly sustainable wildlife tourism. It assesses the extent to which Costa Rican sanctuaries generate positive impacts for native non-human primates. To do so, it applies a Conservation Welfare Assessment Framework as a mixed-method, field-based approach. Findings reveal that sanctuaries can improve primate welfare and conservation outcomes while navigating trade-offs at the nexus of welfare, conservation, and sustainability. Insights are offered to advance sustainable wildlife tourism scholarship and practice.