In disciplines such as moral psychology and media theory, investigations of moral clarity versus ambiguity in narratives are increasingly important. Untested mechanisms have been proposed for how moral clarity and ambiguity might affect audiences. Based on literature regarding joint action and coordinated experiences, we reason that morally clear narratives elicit coordinated responses across audience members, which should increase within-group cooperation. By contrast, we reason that morally ambiguous narratives elicit divergent, uncoordinated responses across audience members, and this experience decreases cooperation. We conducted three independent studies (one using short text narratives, one using feature-length films, and one using morally and emotionally neutral stimuli). Results indicate that moral clarity is indeed associated with subsequently higher levels of group cooperation than moral ambiguity, and the effect cannot be attributed to changes in affect or moral priming.