Cognitive ability and curiosity are significant predictors of academic achievement; yet the processes underlying these relations are not well understood. I drew on ideas from the environmental enrichment hypothesis and the differential preservation hypothesis and hypothesized that epistemic behavior acts as a mediator. Longitudinal data were collected from 1964 individuals in three waves, spanning five years: cognitive ability and curiosity were assessed at time 1; epistemic behavior at time 2; at time 3, grade point average and highest degree of both secondary and tertiary academic education (if applicable) were obtained retrospectively via self-report. I found expected bivariate relations between all study variables, including a significant relation between cognitive ability and curiosity and significant relations of both of these variables with secondary academic performance. Epistemic behavior was related to curiosity and academic performance but, at odds with the hypothesis, did not mediate the relation between cognitive and personality variables and academic performance. It is concluded that the process underlying the behavioral consequences of cognitive ability and curiosity is not environmental enrichment.