There is growing evidence supporting the importance of executive functions, and specifically working memory updating (WMU), for children's academic achievement. This study aimed to assess the specific contribution of updating to the prediction of academic performance. Two updating tasks, which included different updating components, were administered to 97 fourth-grade children. The keeping track task involves retrieval and substitution of information, while the numerical updating task also includes a transformation component. Academic attainment was assessed through standardised tests of verbal comprehension, arithmetic operations, mathematical problems and an assessment made by the teacher. The relative contribution to academic attainment, of the updating measures and measures related to intelligence, was compared. Results showed that both updating tasks are predictive measures of academic attainment, although the numerical updating task appeared to be a more consistent predictor of children's performance. The relationship between updating and academic attainment is discussed, and possible educational implications are considered. The role of the transformation component of WMU is highlighted. This component could make a distinct and independent contribution to performance and, by extension, could be particularly relevant to the prediction of academic achievement.