The aim of this thesis was to examine how experts learn using the theory of deliberate practice. Expert and intermediate Gaelic football players practiced kicking, with their learning being assessed between a pre-test and retention test. A novel method to measure the tenets of deliberate practice during the activity, as opposed to retrospectively, was used throughout the thesis. Findings support previous research on the mechanisms and strategies engaged in by experts as they aim to improve performance and how they differ to lesser-skilled individuals. In line with the theory of deliberate practice, in Chapter 2 and 3 the experts rated practice higher for effort and lower for enjoyment, as well as practicing a more relevant skill in Chapter 2, when compared to intermediates. Moreover, they improved kicking accuracy between pre-test and retention test, whereas the intermediate group did not. In addition, the thesis identified differences between the cognitive mechanisms of experts and intermediates that underpin their respective performance. Expert groups engaged in greater cognitive processing during (Chapter 2 and 3) and between (Chapter 3) practice sessions when compared to intermediates. Chapter 4 examined the impact of applying these expert cognitive processes to the deliberate practice and performance of a youth intermediate group. A training group practiced kicking with an intervention designed to increase cognitive processing, whereas a control group practiced kicking without intervention. Findings support previous research by providing evidence of the outcome of such an intervention on deliberate practice. The training group demonstrated greater cognitive effort and less enjoyment during practice and greater improvements in accuracy after practice compared to the control group. Overall, findings in this thesis support the theory of deliberate practice and extend the research on the role of cognitive processing in effective skill acquisition