--- - |2 Abstract Human prosocial behaviors are supported by early‐emerging psychological processes that detect and fulfill the needs of others. However, little is known about the mechanisms that enable children to deliver benefits to others at costs to the self, which requires weighing other‐regarding and self‐serving preferences. We used an intertemporal choice paradigm to systematically study and compare these behaviors in 5‐year‐old children. Our results show that other‐benefiting and self‐benefiting behavior share a common decision‐making process that integrates delay and reward. Specifically, we found that children sought to minimize delay and maximize reward, and traded off delays against rewards, regardless of whether these rewards were for the children themselves or another child. However, we found that children were more willing to invest their time to benefit themselves than someone else. Together, these findings show that from childhood, other‐ and self‐serving decisions are supported by a general mechanism that flexibly integrates information about the magnitude of rewards, and the opportunity costs of pursuing them. A video abstract of this article can be viewed at: https://youtu.be/r8S0DGe7f8Q - Developmental Science, EarlyView.