Addressing the welfare needs of nonhuman primates in captivity is a significant challenge due to the differences among different species, sexes, ages, dominance groups, and individuals. Interventions that increase species typical behaviors and/or reduce atypical behaviors or stress for one species, group, individual, or context may cause the opposite in others. One area that has recently gained substantial attention is species' cognitive needs, which are particularly important for highly encephalized species such as nonhuman primates. In addition, behavioral and social needs are critical for species that have extended life spans and live in complex social groups. In this chapter, we summarize the cognitive, behavioral, and social needs of primates, focusing on the ways in which they vary among species. As we cannot cover each of the hundreds of primate species, we focus on issues that are likely to be important for most of us involved in research and captive management and draw examples from taxa commonly held in captivity, including apes, macaques, callitrichids, and capuchin monkeys. In each section, we outline the ecological or evolutionary basis of primates' needs and discuss behavioral management strategies designed to meet these needs in captive settings. We hope that this summary of the cognitive, behavioral, and social welfare needs of captive nonhuman primates is useful in informing which enrichment strategies will be the most effective for which species and context.