How do we make sense of others? Social cognition is most often studied in isolation, whereby people are exposed to social stimuli that they perceive, and which influence their actions and thoughts. This has given rise to the notions of Theory of Mind and simulation theory, but, while we undoubtedly have the capacity to reason about others and automatically take others’ perspective, most of our social world consists of interaction, which brings something unique to the table: rather than merely seeing other’s actions, I can see the effect of my actions upon other people. In this talk I will discuss a number of experiments that look at how experiencing the contingencies between my own and others’ reactions shapes how we experience others, and also ourselves. Specifically, I will focus on four questions: (1) How does initiating of joint attention shape how I see others? (2) Do such action contingencies, in eye gaze and gesture, carry an intrinsic reward that can drive my motor learning? (3) Beyond action contingencies, does a dyad of people exhibit dynamics that can predict joint behaviour? (4) If another agent’s reaction is the effect of my action, does that influence my experience of my own agency?