Can transparency interventions improve WASH service provision? We use a randomized experiment to evaluate the impacts of a transparency intervention, a deliberative multi-stakeholder workshop initiated with a community scorecard exercise, in schools in rural Bangladesh. To measure impacts, we combine survey data, direct observations, and administrative data. The intervention leads to moderate but consistent improvements in knowledge of WASH standards and practices, and institutions for WASH service management, but does not improve school WASH service provision or change WASH facility use patterns. Drawing on rich descriptive data, we suggest several reasons why the intervention we evaluate did not improve WASH service outcomes and propose ways to improve the design of future interventions.