There is growing recognition that Transformational Leadership (TFL; Bass & Riggio, 2006) theory may hold significant potential for exploring coaches' influence on athlete development (Vella, Oades, & Crowe, 2013). Although previous research demonstrates that transformational coaching behaviours may have important implications for athlete outcomes (Arthur et al., 2011; Charbonneau et al., 2001), studies examining how coaches apply these behaviours in the youth sport context are limited. The aim of the present work was to investigate an effective youth sport coach's use of transformational coaching behaviours within a program for athletes with disabilities. Semi-structured interviews were conducted with the participant. Interview data were analyzed using an inductive-deductive thematic analysis (Braun & Clarke, 2006), with TFL as the deductive guiding framework. Results revealed eight principles that guided the coach's application of TFL in youth sport: (i) Adopting a person-centred approach, (ii) developing mutually respectful and trusting relationships, (iii) learning from one's mistakes, (iv) believing in one's athletes, (v) recognizing accomplishments, (vi) encouraging athlete input, (vii) adapting to individual needs, and (viii) finding time for fun. Overall, the principles emphasized the creation of caring coach-athlete relationships that fostered athletes' self-determined motivation, confidence, and well-being. These findings provide theoretical insight regarding the application of TFL within the youth sport context and disability sport. Practical recommendations for youth sport coaches who wish to integrate TFL principles into their own coaching practices, as well as potential avenues for future research are discussed.