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 actions to help protect biodiversity could be explained by those same respondents’ biodiversity understanding. Biodiversity understanding was only the sixth most important variable in significantly predicting knowledge of actions to help protect biodiversity. Moreover, biodiversity understanding was the least important variable of those that were significantly related to self‐reported proconservation behavior. Our study indicates that knowledge is a real, but relatively minor, factor in predicting whether members of the public – zoo visitors in this case – will know about specific proenvironment behaviors they can take, let alone whether they will actually undertake such behaviors.