Primate hair is both a substrate upon which essential social interactions occur and an important host-pathogen interface. As commensal microbes provide important immune functions for their hosts, understanding the microbial diversity in primate hair could provide insight into primate immunity and disease transmission. While studies of human hair and skin microbiomes show differences in microbial communities across body regions, little is known about the nonhuman primate hair microbiome. In this study, we collected hair samples (n=159) from 8 body regions across 12 nonhuman primate species housed at 3 US institutions to examine 1) the diversity and composition of the primate hair microbiome and 2) the factors predicting primate hair microbiome diversity and composition. If both environmental and evolutionary factors shape the microbiome, then we would expect significant differences in microbiome diversity across host body sites, host sex, host housing institutions, and host species. We found that the hair microbiomes of these captive primates contained high abundances of gut-, respiratory-, and environment-associated microbiota rather than skin-associated microbiota. We also found that host species identity is the strongest predictor of both hair microbiome diversity and composition, while sex and body region are strong predictors of taxonomic richness and microbiome composition, and institution is a moderate predictor for both diversity and composition. Our results suggest that hair microbial communities are affected by both evolutionary and environmental factors and vary both within and across primate species, and that there may be transmission of microbes across primate body regions. These findings have important implications for understanding the biology and conservation of both wild and captive primates.