The present study investigates the hypothesis that, within personality assessment, the predictive validity of a list of act descriptive sentences will be higher than the validity of a personality inventory on the one hand and that of an adjective checklist on the other. This hypothesis is based on the assumption that people can judge more reliably whether a person will perform a specific act than whether he or she possesses a particular personality trait. Within the validity study, predictors were self‐judgements whereas criteria were peer‐judgements. The predictive validity of the act list was found to be lower than that of the inventory as well as that of the adjective checklist. Moreover, both the act list and the adjective checklist predicted the personality inventory better than the latter predicted the former two. Because of the different functions of self‐ and peer‐judgements within the present study, the former being predictors and the latter criteria, the results are interpreted under the perspective of self‐other attribution differences. Suggestions for constructing a possibly more valid list of act descriptive sentences are given.