Convergent developments across social scientific disciplines provide evidence that ritual is a psychologically prepared, culturally inherited, behavioral trademark of our species. I will draw upon the anthropological and evolutionary science literature to provide a psychological account of the social functions of ritual in group behavior. Solving the adaptive problems associated with group living requires psychological mechanisms for identifying group members, ensuring their commitment to the group, facilitating cooperation with their coalition, and maintaining group cohesion. I will review evidence that the threat of social exclusion and loss of status motivates engagement in ritual throughout development and provide an account of the ontogeny of ritual cognition and behavior. The intersection of these lines of inquiry promises to provide new avenues for theory and research on the evolution and ontogeny of social group cognition. CRISTINE LEGARE is an associate professor of psychology and the director of the Evolution, Variation, and Ontogeny of Learning Laboratory (EVO Learn Lab) at The University of Texas at Austin. Her research examines how the human mind enables us to learn, create, and transmit culture. She conducts comparisons across age, culture, and species to address fundamental questions about cognitive and cultural evolution.