This thesis investigates the developmental trajectory of visuo-spatial working memory as well as the potential influence of acute exercise on working memory performance. Individuals between the ages of 6 and 25 years were randomly assigned to a 30-minute bout of exercise on an elliptical trainer or to a no-exercise control condition. Participants then performed a computerized N-back task to assess working memory. Developmental results suggest that working memory ability continues to develop into early adulthood with the exact trajectory depending on the cognitive demand of the task being assessed. No difference in working memory performance was found between the exercise and control conditions. Thus, acute exercise did not influence performance on the present working memory task, suggesting a need for more research in this area.