Many environmental communication interventions are built on the assumption that increased knowledge will lead to changes in proenvironment behaviors. Our study probes the link between biodiversity-related knowledge and self-reported proconservation behavior, based on the largest and most international study of zoo visitors ever conducted. In total, 6,357 visitors to 30 zoos from 19 countries around the globe participated in the study. Biodiversity understanding and knowledge of actions to help protect biodiversity were significantly related, but only 0.6% of the variation in knowledge of