This study investigated the impact of a transformational leadership training program for youth sport coaches on adolescent athletes' perceptions of transformational leadership and positive developmental experiences. The transformational leadership training program was associated with higher rates of perceived transformational leadership behaviour at follow-up when compared to baseline measures. Importantly, these increases were associated with significantly higher rates of self-reported developmental experiences. Coach training was associated with a predictability and reliability to athlete outcomes that was not evident in athletes of a comparison group. Transformational leadership may provide a theoretically sound foundation for coaching practice and education in the service of facilitating positive developmental outcomes for athletes.