Physical Activity and Wellness Programs (PAWPs), also known as service, general or basic activity programs, play a vital role in providing undergraduates with formal and structured opportunities to develop sport-related skills, fitness and healthy lifestyle habits. However, the literature suggests a general lack of instructional support, development and training for graduate teaching assistants (GTAs) who often serve as lead instructors in such courses. Secondly, there exists a lack of confidence by students, parents and institutional administrators concerning the effectiveness of GTAs as instructors. Research indicates that a GTA’s instructional effectiveness can be increased when provided adequate instructional resources, formative supervision, and use of videotaped instructional analysis. The purpose of this mixed methods case study was to investigate the impact of supervising GTAs using a clinical approach and to explore the benefits of videotaped instructional analysis on GTA instructional development and effectiveness. Data collection consisted of: a) systematic observations, b) individual and focus group semi-structured interviews, c) videotaped analysis of instructional episodes, d) document analyses and e) surveys. Participants consisted of eight GTAs who took part in three clinical evaluative cycles consisting of: a) a pre-observation consultation to discuss instructional goals and strategies; b) a videotaped lesson of the GTA in an instructional setting; and c) a post-observation consultation during which the videotaped lesson was collaboratively discussed for instructional strengths, weaknesses and modifications. Throughout the academic semester the GTAs took part in informal and formal seminars focused on discussing their instructional issues, experiences and facilitating greater instructional competence. Results of the study indicated that a clinical supervisory approach to GTA training and the use of videotaped instructional analysis improved multiple aspects of their teaching effectiveness. The findings were as follows: a) GTAs reported a greater sense of preparedness concerning their teaching due to pre- and post-observation consultation; b) the use of videotaped instructional analysis allowed for effective individual and group consultation concerning improving tasks description, classroom management, and communication; c) GTAs identified a higher sense of appreciation as instructors due to increased formal supervision by departmental administration; and d) GTAs were able to compare their actual performance as instructors with pre-determined objectives thus facilitating an awareness of their instructional competence. Overall, the use of a clinical supervisory approach combined with videotaped analysis of teaching allowed for the GTAs to improve their instructional effectiveness and sense of self-adequacy as instructors.Keyword(s): administration/mgmt, college level issues, physical activity