The purpose of this study was to explore the use of action research as a framework to investigate cooperative learning and tactical games as instructional models in physical education (PE). The teacher/researcher taught a tennis unit using a combination of Cooperative Learning and Teaching Games for Understanding to three classes of boys aged 11-12. Data collection included: teacher and pupil evaluations of skill, pupil reflections on the lessons, pupil interviews, teacher field journal and the documentation and course materials from the unit of work. Data analysis was conducted using inductive analysis and constant comparison (Denzin and Lincoln, 1994; Lincoln and Guba, 1985). The results of this research reinforce the concept that the implementation of any new pedagogical approach is time-consuming and highly labour intensive (Fullan, 1999). The conceptual shift the teacher/researcher made to relinquish control to students was one of the most difficult, but important, outcomes of this action research process. (Contains 3 figures.)