The overall purpose of the study was to investigate prospective actor and partner effects (cf. Kenny, Kashy, & Cook, 2006) of interpersonal efficacy beliefs in relation to relationship commitment, satisfaction, and effort within coach-athlete dyads. Fifty youth tennis players (mean age = 15.52 years, SD = 1.45) and their coaches (mean age = 40.17 years, SD = 13.71) provided data related to their self-efficacy, other-efficacy, and relation-inferred self-efficacy (RISE) beliefs mid-way through the competitive season. Three months later, participants provided data regarding personal effort, as well as relationship commitment and satisfaction. Actor-partner interdependence model analyses revealed positive actor effects for self-efficacy in relation to effort, and for other-efficacy in relation to commitment, effort, and satisfaction. Partner effects for other-efficacy were found in relation to relationship commitment and effort. Finally, actor and partner effects were also evident for RISE beliefs; however, these relationships were moderated by the individual's role (i.e. athlete or coach), such that the direction of actor and partner effects differed for athletes and coaches. Implications for fostering effective coach-athlete relationships are discussed.