A common method to promote behavior change, particularly in contexts related to collective action, is to reference a social norm and ask people to comply with it. We argue that such appeals will be more effective when they couch the norm as an invitation to work with others toward a common goal. In six experiments, we found that working-together normative appeals, which invited people to "join in" and "do it together," increased interest in (Experiments 1, 4, and 5) and actual charitable giving (Experiment 2), reduced paper-towel use in public restrooms (Experiment 3), and increased interest in reducing personal carbon emissions (Experiment 6). By contrast, normative-information appeals, which included the same normative information but no reference to working together, did not affect interest or behavior. Mediation analyses suggest that working-together normative appeals were more effective because they fostered a feeling in participants that they were working together with others, which increased motivation, while inducing less social pressure, which undermined effectiveness. Results show how the very collective nature of collective action problems can be leveraged to promote personal behavior change and help solve societal problems. (PsycInfo Database Record (c) 2021 APA, all rights reserved).