Most cooperative interactions involve interpersonal trust and the expectation of mutual reciprocation. Thus, understanding when and how humans acquire interpersonal trust can help unveil the origins and development of children's cooperative behavior. Here, we investigated whether prior sociomoral information about trading partners modulates the choice of preschool (4--5 years) and school-age children (7-8 years) to share their own goods in a child-friendly version of the trust game. In this game, the trustee partner can repay the child's initial investment or keep everything and betray the trustor. In two studies, we addressed whether trust is modulated by trustees exhibiting prosocial versus antisocial behaviors (Study 1, "helper and hinderer"), or respect-based versus fear-based power (Study 2, "leader and bully"). Preschoolers trusted the leader reliably more than the bully, and the hinderer reliably less than a neutral agent. The tendency to trust the helper more than the hinderer increased with age as a result of the increased propensity to trust the prosocial agent. Overall, these findings indicate that, by age 5, children understand complex cooperative exchanges and start relying on sociomoral information when deciding whom to trust.