A multidimensional inventory was developed to assess competitiveness as the desire to approach and strive for success in sport situations. A 32-item inventory was administered in two separate studies to samples of male and female students enrolled in competitive and non-competitive skills classes (n=237 in Study 1; n=218 in Study 2). Factor analyses revealed consistent three-factor solutions across studies, with the factors representing competitiveness (e.g., enjoyment of competition, striving for success in competition), win orientation (e.g., striving to win in competition), and personal goal orientation (e.g., striving to reach personal standards in competition). Alpha coefficients and item-to-total correlations revealed high internal consistency for each factor. Furthermore, students in competitive classes had significantly higher competitiveness scores than students in non-competitive skills classes, providing initial support for the validity of the inventory. The factor stability, internal consistency and initial validity evidence suggest that the Sport Competitiveness Inventory can be a valuable instrument for assessing competitiveness as a multidimensional, sport-specific individual difference variable. Appendices include the Competitiveness Inventory Items and the Sport Orientation Questionnaire. (Author/JD)