The social psychology of collective mobilization and social protest reflects a long-standing interest within this discipline in the larger question of how social change comes about through the exercise of collective agency. Yet, within this very same discipline, different approaches have suggested different motivations for why people protest, including emotional, agentic, identity, and moral motivations. Although each of these approaches first tended toward development of insulated models or theories, the next phase has been more integrative in nature, giving rise to multi-motive models of collective mobilization and social protest that combined predictions from different approaches, which improved their explanatory power and theoretical scope. Together with this first development toward integration, a second development has also clearly left its mark on the field. This development refers to the rapid internationalization of the field, with studies on collective mobilization and social protest being conducted across the world, leading to very diverse participant samples and contextual characteristics. These studies typically also vary methodologically, including survey, experiment, interview, longitudinal, and other methods. This second trend—toward diversity—fits well with the first integrative trend and will lead to more in-depth and integrative understanding of the social-psychological workings of collective mobilization and social protest. However, this will require innovative conceptual and empirical work in order to map the structural (particularly, political and cultural) conditions under which different motivations matter with respect to mobilization and protest.