In this talk, I will describe the research conducted by scientists from Lincoln Park Zoo’s Lester E. Fisher Center for the Study and Conservation of Apes, with chimpanzees, western lowland gorillas and Japanese macaques. Through the use of touchscreen technology and more naturalistic foraging and tool-use tasks our team runs studies to understand the primates’ behavior, cognition and welfare. I will also discuss my own research interests in primate social cognition, by focussing on primates’ behavioral responses to the presence and actions of others and how they adjust their behaviour to maximize their own gains. Individuals can observe and replicate the actions of others, or the outcomes of their actions, to accelerate behavioural acquisition of techniques to obtain rewards (social learning). However, such observations can reveal inequality in the rewards gained by different group members. Therefore, I will also discuss how certain primate species have been shown to respond negatively when receiving less than a social partner (inequity aversion), a response which may protect individuals against cheating. Interestingly, there is variation both within and between species in their sensitivity to the actions of others and their responses to them. Thus, a comparative framework is needed when studying what is meant by ‘primate social cognition.’