The relationship between executive functions (inhibitory control and working memory) and metacognitive skills was investigated by applying correlational and regression analyses to data collected from two groups of children. To date, research in this area has lacked a theoretical model for considering these relationships; here we propose and test such a model. Our model hypothesises that if metacognitive skills are either monitoring or control processes, depending on the direction of information flow between the meta- and object-level, then each executive function should relate to one of these processes. Further, the contribution that executive functions and metacognitive skills make to educational achievement was examined. Results indicated that executive functions were more related to metacognitive skills in 5-year-olds than in 7-year-olds, and metacognitive skills were the most important predictors of educational achievement across both age groups. These data support an interpretation that the two skills are not identical to one another, and that executive functions could be "necessary but not sufficient" antecedents to metacognitive skills, i.e. younger children's immature executive functions may limit their metacognitive skill use.