Abstract
Play is a complex social behavior that is highly conserved across mammals. In most species, males engage in more frequent and vigorous play as juveniles than females, which reflects subtle yet impactful sex differences in brain circuitry and development. In this protocol, we describe a behavioral testing paradigm to assess social play in male and female juvenile rats. We highlight the behavior scoring criteria for distinguishing rough-and-tumble play from other play-related social behaviors. By analyzing both sexes, play behavior can be leveraged as a powerful tool to understand the sex-specific development and expression of social behavior.