This paper reports two related studies intended to explore the interactions between children's metacognitive abilities, their working memory capacity, the development and selection of strategies and their performance on problem-solving tasks, In the first study, a sample of 20 children aged 5 and 6 were presented with a reclassification task. In the second study, a sample of 72 children aged 6, 8 and 10 were presented with a multidimensional discrimination learning (MDL) task. Data was collected related to the children's metacognitive abilities, working memory capacity, response strategies and task performance. The results indicated that performance on both tasks was dependent upon developmentally changing interactions between these various aspects of cognitive functioning. In particular, the relationship of working memory capacity to performance was dependent upon metacognitive abilities. The results also suggested that metacognitive awareness did not directly affect performance, but that such a relationship was dependent upon the development of strategic control. The implications of these results for understanding V-shaped behavioural growth and other common developmental patterns are discussed. Within the educational sphere, the study emphasises the significance and possibility for children as learners offostering certain kinds of metacognitive ability.