Successful coach-athlete relationships contribute to enhanced performance and personal outcomes. Especially in individual sports, a coach and athlete form a dyadic relationship where their thoughts, emotions, and behaviours are mutually interdependent. Additionally, in youth sport, parents are often actively involved in their child's sporting experience. However, it remains unclear how coaches build and maintain successful coach-athlete-parent relationships within the elite youth sport setting. Thus, the purpose of this study was to explore how tennis coaches developed high-quality relationships with their athletes, including their parents. Five elite tennis coaches were purposefully recruited based on the recommendation of Tennis Canada. Data were collected through two semi-structured interviews and three story completion tasks. A thematic analysis was used to generate themes across the semi-structured interviews and story-completion tasks. Results outlined that coaches established close, trusting relationships with tennis players, by prioritizing the management of parental involvement. Coaches believed parents played an instrumental role in their child's athletic experience and needed parents to communicate similar, constructive messages to the athletes. In order to facilitate cooperation between the parent(s), athlete, and primary coach, coaches shared their athlete-centered philosophy by helping parents adopt supportive communication and behaviours. More specifically, coaches explained athletes' long-term goals, emphasizing the importance of praising effort over performance outcomes, and encouraging parents to control their emotions throughout competition. Overall, it appeared that tennis coaches believed managing parental involvement played a crucial role in their ability to establish successful coach-athlete relationships.