Children need to build trust in their primary caregivers or significant others, as well as people who are unrelated to them, including those who belong to different social groups. The present chapter focuses on children's trust in unfamiliar individuals. How do they determine who to trust? Does putting trust in another person operate differently depending on the specific issue at hand? To address these questions, we differentiate between two forms of trust: children's trust in others' epistemic states to learn from others (epistemic trust) and trusting others for social support and reassurance (social trust), for example, when to expect that interaction partners will be truthful and keep promises. We first review the literature on epistemic trust to show that young children seem to value others' accuracy and competence when learning from them, even when these individuals are from different linguistic or racial groups than their own. We then present findings on social trust suggesting that young children trust those who are well-meaning and who keep their promises. Finally, we raise the question of whether there are environmental influences on the interaction of both epistemic and social trust with intergroup factors such as race, and we propose that research with infants will be useful to better illuminate the developmental roots of human trust.