Children's causal learning has been characterized as a rational process, in which children appropriately evaluate evidence from their observations and actions in light of their existing conceptual knowledge. We propose a similar framework for children's selective social learning, concentrating on information learned from others' testimony. We examine how children use their existing conceptual knowledge of the physical and social world to determine the reliability of testimony. We describe existing studies that offer both direct and indirect support for selective trust as rational inference and discuss how this framework may resolve some of the conflicting evidence surrounding cases of indiscriminate trust. Importantly, this framework emphasizes that children are active in selecting evidence (both social and experiential), rather than being passive recipients of knowledge, and motivates further studies that more systematically examine the process of learning from social information.