We draw from transformational leadership theory (Bass & Riggio, 2006) to develop a reliable and valid measure of transformational teaching, for use within school-based physical education contexts. In Phase 1, we utilized established instrument development procedures, involving teachers, students, and experts in transformational leadership theory to ensure that items exhibited sound content validity, and were developmentally appropriate. In Phase 2, multilevel confirmatory factor analytic procedures with 2761 adolescents supported the factorial validity of the Transformational Teaching Questionnaire. In Phase 3, concurrent validity of the TTQ was supported by positive relationships between transformational teaching and adolescent self-determined motivation and positive affect.