One of the hallmark features of autism spectrum disorders (ASD) is dysfunction in social perception, attention, and interaction. Nonetheless, significant individual variation in these features frustrates diagnosis and challenges the development of effective treatments. To address this gap, this research will develop a model for studying the genetic, contextual, and neurobiological contributions to social behavior phenotype in rhesus macaques. The research will first characterize variability in social reward, social attention, and social aggression in a natural population of rhesus macaques, then assay key genes thought to contribute to social behavior and its dysfunction in humans (including in ASD), and finally test the impact of potential therapeutic interventions in the laboratory in macaques of known genotype. Integrating these methods will lead to development of a biologically predictive model of heterogeneity in primate social behavior that will inform understanding of the basic genetic, developmental, and neurobiological causes of phenotypic heterogeneity in autism.