Children show economic trust for both ingroup and outgroup partners

•Study 1 examined 4 and 6 year olds’ trust in others’ reciprocal prosociality.•Study 2 investigated 6−7 year olds’ trust in others’ generosity.•In both studies, children generally trusted at high levels.•In both studies, children showed ingroup biases on attitudinal measures.•They did not distinguish between ingroup and outgroup partners in their trust choices. Trust is a critical aspect of human cooperation, allowing individuals to overcome the risks posed by such interactions because of others’ presumed cooperative inclinations. Adults sometimes mitigate these risks by preferentially trusting members of their own social group, yet it is currently unclear if the early emergence of children’s trust in others’ cooperative tendencies is affected by their intergroup psychology. Here we tested whether group membership impacts two key aspects of trust-based cooperation in young children – their trust in others’ willingness to reciprocate an investment (assessed using the Investment Game, Study 1), and their trust in others’ generosity (assessed using the Faith Game, Study 2). In both studies, children assigned to novel and otherwise arbitrary groups demonstrated general preferences for ingroup members on several measures. However, group membership did not influence their decisions about economic trust. In Study 1, 4- and 6-year-old children showed high levels of trust in both ingroup and outgroup members’ tendency to reciprocate an investment. In Study 2, 6- to 7-year-old children similarly showed high levels of trust in ingroup and outgroup members’ generosity, and they did so regardless of whether their group membership was a matter of common knowledge between themselves and the trustee. These findings show that young children’s preferences for ingroup members do not result in bias due to shared group membership when making economic trust decisions. Rather, children tend to exhibit trust in the cooperativeness of others regardless of group membership.