Efforts to control neglected tropical diseases have increasingly focused on questions of implementation. But how should we conceptualize the implementation process? Drawing on ethnographic fieldwork between 2010 and 2012, in this article I explore efforts by a small-scale public–private partnership to use private veterinarians to sustainably control zoonotic sleeping sickness in Uganda. With a fundamental tension between business incentives and vector control, I show how divergences in knowledge, power, values, and social norms shaped project implementation and community responses. Reflecting more widely on the relationships between project plans and local realities, I argue that these encounters reveal the heuristic value in approaching global health interventions as evolving ‘social experiments.’ This metaphor reveals the uncertainty inherent to dominant narratives and models, the role of available expertise in defining the limits of action, and the need for continuous adaption to synchronize with emergent social and institutional topographies.