Numerous scholars have stressed the importance of personal and social responsibility in physical activity settings; however, there is a lack of instrumentation to study the implementation of responsibility-based teaching strategies. The development, content validity, and initial inter-rater reliability testing of the Tool for Assessing Responsibility-Based Education (TARE) are described here. Inter-rater agreement was calculated for paired observations focused on 2 different teachers delivering a total of 18 separate physical education lessons for students in grades 1 through 6. Findings indicate that the Tool for Assessing Responsibility-Based Education provides scores with adequate inter-rater reliability. The procedures employed in this study proved feasible and enable observers to characterize the implementation of responsibility-based teaching in physical education. The Tool for Assessing Responsibility-Based Education has numerous research and training applications relative to the Teaching Personal and Social Responsibility model (Hellison, 2003) and the national content standards for K-12 physical education, specifically Standard 5: Exhibits responsible personal and social behavior that respects self and others in physical activity settings (National Association for Sport and Physical Education, 2004). (Contains 7 tables.)