This study examined determinants of junior tennis players' motivation to continue involvement using the sport commitment model as the theoretical framework (20). Based on the sport enjoyment literature, a version of the original sport commitment model (i.e., all determinants directly predict commitment) and a revised model where enjoyment was a mediator of the relationships between determinants and level of commitment were tested. Tennis players (N = 198; ages 10-18 years) completed self-report questionnaires on the constructs of interest. Hypothesized relationships among variables were tested using structural equation modeling. Results provided support for both the original and mediational models, with enjoyment exerting the strongest effect on tennis commitment in both models. An alternative model was tested where both direct and indirect effects through enjoyment on commitment were specified. The alternative model was accepted as most theoretically appealing because determinants of commitment and sources and consequences of sport enjoyment were accounted for within the larger conceptual model.