Recent meta-analytical findings have corroborated the notion of openness as a dichotomous personality dimension that encompasses two distinct aspects, namely intellectual and senso-aesthetic openness. This article investigates the associations of these two aspects with objective and subjective academic achievement as well as their incremental validity over and interaction with the two conscientiousness aspects industriousness and orderliness. Cross-sectional data from 424 undergraduate students suggested that a) intellectual openness was a strong positive predictor of academic achievement, whereas senso-aesthetic openness was a moderate negative predictor, b) openness aspects showed substantially more incremental validity over conscientiousness aspects than vice versa, and c) intellectual openness and orderliness interacted in the prediction of objective academic achievement. These results emphasize the relative importance of openness in postsecondary education and provide promising perspectives for further research.