Longitudinal data from the children of the National Longitudinal Survey of Youth (NLSY) were used to assess how well measures of short-term and working memory and attention in early childhood predicted longitudinal growth trajectories in mathematics and reading comprehension. Analyses also examined whether changes in memory and attention were more strongly predictive of changes in academic skills in early childhood than in later childhood. All predictors were significantly associated with academic achievement and years of schooling attained, although the latter was at least partially mediated by predictors’ effect on academic achievement in adolescence. The relationship of working memory and attention with academic outcomes was also found to be strong and positive in early childhood, but non-significant or small and negative in later years. The study results provide support for a “fade-out” hypothesis, which suggests that underlying cognitive capacities predict learning in the early elementary grades, but the relationship fades by late elementary school. These findings suggest that whereas efforts to develop attention and memory may improve academic achievement in the early grades, in the later grades interventions that focus directly on subject matter learning are more likely to improve achievement.