For many coaches, athletes, and sport psychologists, mental toughness is considered to be one of the most essential characteristics athletes must possess in order to be successful in sport. While there is yet to be a consensus on what mental toughness means, the idea that coaches are one of the main influences of mental toughness development in athletes has been supported by many. The purpose of this study was to examine how the coach-athlete relationship can affect mental toughness development in athletes and if coaching behaviors are perceived depending on how athletes view their relationship with their coach. Participants of this longitudinal dual-methods study were 16 female volleyball players from a single NCAA Division II school. Athletes completed a demographic questionnaire, the Mental Toughness Scale (MTS-11), Coach-Athlete Relationship Questionnaire (CART-Q), Coaching Behaviors Scale for Sport (CBS-S), and a total of three different open-ended questions at the pre- and post- season. Pearson r correlation analysis did not find significance between mental toughness and the perceived quality of the coach-athlete relationship; however, there was significance in the relationship between coaching behaviors and the coach-athlete relationship quality. A Paired t-Test analysis also found significant changes in how athletes viewed the quality of the coach- athlete relationships from pre- to post- season. A total of 11 themes were found after a thematic analysis was conducted for the responses to the open-ended questions. This study aimed to explore athletes’ ideal coach-athlete relationship and how this relationship can be achieved to maximize player development and performance.