What is the nature of children's trust in testimony? Is it based primarily on evidential correlations between statements and facts, as stated by Hume, or does it derive from an interest in the trustworthiness of particular speakers? In this essay, we explore these questions in an effort to understand the developmental course and cognitive bases of children's extensive reliance on testimony. Recent work shows that, from an early age, children monitor the reliability of particular informants, differentiate between those who make true and false claims and keep that differential accuracy in mind when evaluating new information from these people. We argue that this selective trust is likely to involve the mentalistic appraisal of speakers rather than surface generalizations of their behavior. Finally, we review the significance of children's deference to adult authority on issues of naming and categorization. In addition to challenging a purely inductive account of trust, these and other findings reflect a potentially rich set of tools brought by children to the task of learning from people's testimony. © 2007, Cambridge University Press. All rights reserved.