This study examined the development of school-related causality beliefs which are children's generalized perceptions of the utility or power of different categories of specific means in producing school outcomes. Based on the action theory perspective, we analyzed the developmental model of these beliefs as well as the trajectories of the five perceived causes of school success and failure: ability, effort, luck, teacher's help, and unknown causes. On a 5-year longitudinal study, following a group of 63 students over an 8-year period (from the second to the ninth grades), using hierarchical linear models, intraindividual changes and interindividual differences in these changes were identified; also, factors that might account for this variability were tested. The results showed a decrease of the effectiveness attributed to the various causes, but their differentiated trajectories, and a relative independence of gender and achievement factors (engagement and school grades) in the evolution of these beliefs. School children in the lower grades value most highly ability and effort as causes of school success. Student's beliefs about the causes of school performance become both more conservative and more differentiated along schooling, which is probably a normative general tendency. Findings from this longitudinal study corroborate, to a large extent, a consistent set of important developmental findings based on previous cross-sectional designs.