In Study 1, 60-item sets of behavioural acts exemplifying a personality trait were elicited for each of 40 traits. Each set of behaviours was then rated by 66 students for their inferential meaning (prototypicality) and evaluative meaning (valence). As predicted, the traits differed in the degree of congruence between the two meanings of their exemplifications. In Study 2, 80 subjects were presented with behaviour descriptions varying in their prototypicality for congruent or incongruent traits, and were asked for trait inferences and evaluations. The higher prototypicality, the more the inferred traits were similar to the original ‘criterion’ traits and the more extreme were the ascriptions of those freely inferred traits. As predicted on the basis of accentuation theory, behaviours exemplifying congruent traits led to more extreme trait inferences and evaluations than behaviours exemplifying incongruent traits. We conclude that trait inferences and evaluations are based both on prototypicality of behavioural acts and on structural properties of the traits examplified by these acts.