The purpose of this qualitative comparative case study was to examine the implementation fidelity of a program designed to deliverthe Teaching Personal and Social Responsibility (TPSR) model (Hellison, 2003) through physical education and its relationshipwith short-term outcomes for elementary school students. The research questions were: (a) was the program implemented with fidelity, and (b) did better fidelity yield better student outcomes. Thus, we conducted a study on the implementation process used by twoteachers who delivered the same program in two physical education classes in two different elementary schools in Spain. Data sourcesincluded observations and interviews with teachers and nonparticipant observers. Findings indicated that fidelity of implementationin Case 1 was higher and most children in those classes acquired the first three of five TPSR responsibility levels. Implementation fidelity in Case 2 was weaker and achievement of responsibility goals was minimal (only the first of five levels) and less stable for thosestudents. This study is the first to directly examine the connection between TPSR implementation fidelity and student outcomes.