This study presents the development and preliminary validation of the Collective Efficacy Questionnaire for Sports (CEQS). The study was conducted in 3 phases. In Phase 1, a 42-item questionnaire was developed and tested with 271 college-aged student-athletes. An exploratory factor analysis revealed 5 collective efficacy factors with 27 items retained. In Phase 2, again using college-aged student-athletes (N = 286), confirmatory factor analysis (CFA) supported a 5-factor, 20-item measure. These factors were named Ability, Effort, Preparation, Persistence, and Unity. In Phase 3, preliminary support for the construct validity (i.e., convergent, predictive, and discriminant validity) of the CEQS was obtained by examining correlations among the CEQS subscales and a measure of team cohesion (Group Environment Questionnaire; Widmeyer, Brawley, & Carron, 1985). A second CFA was conducted on the CEQS to cross-validate the measure. Combined results establish preliminary support for the CEQS. (Contains 9 tables and 1 footnote.)