Knowledgeable agents always choose what they like best, thus revealing their preferences. But naïve agents only choose what they believe they like best, and may end up disliking their choice. As such, sensitivity to an agent’s prior experience is critical for interpreting their behavior. Here we show that four- and five-year-olds expect knowledgeable agents, as compared to naïve agents, to have stable choices that lead to higher rewards (Experiments 1 and 2). Additionally, we show that four- and five-year-olds can infer which of two agents is naïve given information about the rewards they obtained and the stability of their choices (Experiments 3 and 4). These results show that young children understand that beliefs and desires are interconnected and that, in addition to having uncertainty about the world, agents can also be uncertain about their own desires.