Even infants expect agents to act rationally in pursuit of their  goals. However, little research has looked at whether young  children expect other agents to learn rationally. In the  current study, we investigated 4.5- to 6-year-olds’ reasoning  about another agent’s beliefs after the agent observed a  sample drawn randomly or selectively from a population.  We found that those children who could correctly track both  the true state of the world and the other agent’s initial beliefs  expected the other agent to learn rationally from the data.  Critically, this inference depended upon but could not be  reduced to either the child’s own understanding of the world,  or the child’s own inferences from the sampling process,  suggesting that the ability to integrate these component  processes underlies a developing understanding of the way  in which evidence informs others’ beliefs.