In this paper the concept of "ecological personality scales" is introduced. These are contextualized inventories with a high ecological validity. They are developed in a bottom-up or qualitative way and combine a relatively high trait specificity with a relatively high situational specificity. An ecological conscientiousness or time management scale for Ph.D. candidates was developed. It significantly predicted Ph.D. performance criteria and showed incremental validity beyond Big Five (Study 1) and narrow trait and frame-of-reference scales (Study 2). These findings suggest that an ecological approach may contribute to further improving the criterion validity of personality measures