Human cognitive abilities are remarkable, but not exceptional. In light of evolution, humans are an extreme primate on one end of an already-sophisticated spectrum. One hypothesis for explaining the evolution of primate cognition is that living in groups selected for a “social mind”, a larger brain and complex cognitive abilities to aid in solving a myriad of social challenges. This hypothesis has garnered considerable support from experimental paradigms in captivity, however, these studies are often void of normal social interactions. Understanding the selective pressure of social challenges on primate cognition, and the adaptive value of these choices, requires studying the social mind in a social context. My research program examines how nonhuman primates actually make decisions in their social world, what factors impact these choices, and ultimately why these decisions are adaptive. In this talk, I focus on decision-making during cooperation and conflict, two situations in which making the wrong choice can have significant fitness consequences. First, I examine how conflict influences cooperative choices in capuchins, and the role oxytocin may play in promoting cooperation during conflict. Second, I present novel methods and some preliminary findings on how wild capuchins solve novel problems and tackle cooperative tasks. By combining the best aspects of naturalistic field work, highlighting the emergence of social challenges, and the best aspects of tightly controlled experiments, highlighting the mechanisms of social choices, my research offers a promising avenue for understanding the importance of sociality, cooperation, and conflict on primate cognitive evolution.