In this review, we ask how looking at people’s faces can influence prosocial behaviors toward them. Components of this process have been studied in two disparate literatures: one focused on the perception of faces and judgments based on them, using both psychological and neuroscience approaches, and a second focused on actual social behaviors as studied in behavioral economics and decision science. Bridging these disciplines requires a mechanistic account of how processing of particular face attributes or features influences social judgments and behaviors. We review these two lines of research and suggest that combining some of their methodological tools may reveal the bridging mechanistic explanations.