Many development agencies and governments now seek to engage directly with local communities, whether as a means to the realization of more familiar goals (infrastructure, healthcare, education) or as an end in itself (promoting greater inclusion, participation, well-being). These same agencies and governments, however, are also under increasing pressure to formally demonstrate that their actions 'work' and achieve their goals within relatively short timeframesexpectations which are, for the most part, necessary and desirable. But adequately assessing 'community-driven' approaches to development requires the deployment of theory and methods that accommodate their distinctive characteristics: building bridges is a qualitatively different task to building the rule of law and empowering minorities. Moreover, the 'lessons' inferred from average treatment effects derived from even the most rigorous assessments of community-driven interventions are unlikely to translate cleanly to different contexts and scales of operation. Some guidance for anticipating and managing these conundrums are provided.