Orienteering has received little research interest within psychology. Therefore, the objectives of this thesis were to identify constraints inherent in orienteering, and adaptations to constraints by experienced orienteers that were responsible for performance increases. Three studies were conducted to meet these objectives. In the first study, 17 elite orienteers were interviewed and a grounded theory of expert cognition in orienteering was developed. Managing attention to the map, environment, and travel, was identified as a fundamental constraint in orienteering. Results revealed adaptations by experts to this constraint, characterised by cognitive skills such as planning. The second study explored the relationship between orienteering experience and the allocation of attention to the map, environment, and travel. While orienteering, 20 more and 20 less experienced orienteers wore a video camera and verbalised what they were attending to (map, environment or travel) at any given time. Films were coded at each point in time in terms of what the participant was attending to and whether they were moving or stationary. Experienced orienteers were faster than less experienced orienteers, and better at attending to the map without stopping. Planning was one skill proposed to explain these differences. The final study investigated the use of two planning heuristics reported in the first study: attending to the start first and planning forward to the control, and attending to the control first and planning backwards to the start. Two process tracing methods were employed while 20 experts and 20 novices planned orienteering legs. Orienteers were also interviewed about heuristic use. Results indicated that experts attended to the control, and novices to the start, first when planning. There was some evidence that novices worked forwards, and experts worked backwards when planning. The results of the thesis have implications for expertise research, and skill acquisition within orienteering.