The theoretical literature on social norms is multifaceted and at times contradictory. Looking at existing reviews, we aimed to offer a more complete understanding of its current status. By investigating the conceptual frameworks and organizing elements used to compare social-norms theories, we identified four theoretical spaces of inquiry that were common across the reviews: what social norms are, what relationship exists between social norms and behavior, how social norms evolve, and what categories of actors must be considered in the study of social norms. We highlight areas of consensus and debate in the reviews around these four themes and discuss points of agreement and disagreement that uncover trajectories for future empirical and theoretical investigation.