We explore the dynamics of expectations in international forest conservation and development programs, and the impacts and implications of (unfulfilled) expectations for actors involved. Early stages of new international conservation and development programs, often involving pilot projects designed to test intervention concepts at village level, are characterized by large amounts of resources and attention, along with high expectations of success. However, evidence shows that these early expectations are rarely fulfilled. Despite this repeated pattern and growing engagement with expectations in critical conservation and development literature, little is known about the dynamics of expectations in conservation and development pilot projects. We address this knowledge gap first by exploring concepts from the sociology of expectations. We then unpack expectations in a case study of REDD+ pilot projects in Tanzania, using extensive qualitative data reflecting the perspectives and experiences of a wide range of actors involved. Our study finds that expectations play a performative role, mobilizing actors and resources, despite uncertainty identified among policy-makers and practitioners. We also find that once raised, expectations are dynamic and continually mediated by actors and social contexts, which conflicts with attempts to ‘manage’ them. We argue therefore that a trade-off exists between fully piloting new initiatives and raising expectations. We also argue that failure to address this trade-off has implications beyond pilot project objectives and timelines, which are experienced most acutely by village communities. We argue for more critical engagement with expectations and the embedding of accountability for expectations in conservation and development practice. Our findings also challenge the discourse of ‘needing’ to pilot, which prioritizes awareness, impact and innovation without fully considering the potential negative impact of unfulfilled expectations.