Trait conceptions, such as smart, antisocial, and shy, can serve as tools for interpreting and making predictions about the social world. An understanding of children?s trait conceptions can lead to important insights into the way children acquire an understanding of human mental life. The present study was designed to examine positivity biases in reasoning about traits among 7- to 8-year-olds, 11- to 13-year-olds, and adults.The central question is whether there are systematic valence effects in reasoning about these traits; that is, whether children?s inferences differ when children reason about positive versus negative traits that lie along a single trait dimension. Participants were presented with four sets of questions that relate to different aspects of trait reasoning: malleability, stability, origin, and inference criterion. The four question sets appeared in random order, determined separately for each participant. provides clear evidence that children across a range of ages place more emphasis on positive information than on negative information in both the academic and social domains. Results suggest that some but not all of these tendencies become weaker across development. Further research will be needed to discover more about the consequences of these tendencies and the contextual factors that may influence them. (Contains 4 tables.)