How do students' conceptualize the causes of their own academic successes and failures? Taking a phenomenological approach, students identified the causes of their performance immediately following return of a graded examination. We then used factor and item analyses to organize causes that were identified by a substantial number of students into meaningful conceptual clusters, and confirmed those empirically derived clusters in a different sample of students using confirmatory factor analysis. That analysis indicated that students' descriptions of the causes of their outcomes were consistent with a hierarchical model in which specific causes such as effort and ability are subsumed in one of two more general clusters--facilitating causes and inhibiting causes--but many students explained their outcome by identifying causes from both categories. At a practical level, measuring unitary causes proved to be a reliable and valid way of assessing spontaneous thoughts about what causes academic outcomes.