A questionnaire consisting of 223 sexual motive items was administered to 904 respondents whose responses were subjected to factor analysis. Four items were selected from each of the 18 sexual motives that emerged in the factor analysis. A second questionnaire consisting of the 72 sexual motive items and several validity measures was administered to 487 respondents. A factor analysis based on their responses replicated the factor structure that emerged in the first factor analysis. The result was a 72-item inventory of 18 sexual motives with good to excellent internal reliability, adequate test-retest reliability, and substantial convergent and discriminant validity. The Comprehensive Sexual Motives Inventory Catalogue (COSMIC) includes scales for arguably all of the sexual motives measured in the four inventories in the literature which only have the motives of love and pleasure in common. The COSMIC also includes eight new motives not present in any of the current inventories: The results also provide information on relationships between each motive and several personality measures and sexual risk factors.