Athletes’ intrapersonal regulation of emotions has maintained a dominant focus in the sport-emotion literature; yet, coaches’ emotions may also influence athlete outcomes (Friesen et al., 2013). Thus, the objective of this investigation was to explore the relationship between coaches’ emotions and athletes’ psychosocial development. Male head coaches (N = 9) and their respective female adolescent competitive club soccer athletes (N = 153, Mage = 14.54) were recruited from southeastern Ontario. For each team, coach-athlete interactions were audio and video recorded during two training sessions. Additionally, athletes completed questionnaires assessing the 4 Cs of Positive Youth Development (Vierimaa, Erickson, Côté, & Gilbert, 2012). The Assessment of Coach Emotions (ACE) systematic observation instrument (Allan, Turnnidge, Vierimaa, Davis, & Côté, 2014) was employed for the coding of all video-recorded data. Cluster analyses based on the proportional frequencies of observed emotion-behaviour combinations revealed the presence of two distinct groups: “calm, inquisitive” coaches (n = 6) and “intense, hustle” coaches (n = 3). No significant effects of group membership were found for Confidence, Competence, or Connection to the coach; however, using Pillai’s trace, there was a significant effect of group membership on Character, V = .110, F(2, 131) = 8.097, p < .001. Separate one-way ANOVAs revealed a significant effect of coach group on athletes’ prosocial behaviours, F(1, 132) = 6.067, p = .015, and antisocial behaviours, F(1, 71.193) = 4.985, p = .029. More specifically, athletes of “calm, inquisitive” coaches scored significantly higher on ratings of prosocial behaviours, t(132) = 2.463, p = .015, and lower on ratings of antisocial behaviours, t(71.193) = -2.233, p = .029, than athletes of “intense, hustle” coaches. Despite the comparable success of all coaches in facilitating 3 of the 4 Cs, emotional qualities of coaches’ behaviours appear to have a distinct influence on Character development of young athletes.