Study Objective: Grounded in Self-Determination Theory (SDT; Deci & Ryan, 2002), the main aim of this study was to explore the effects of athlete and athletic therapists' motivations as they impact the rehabilitation process following a sports injury. Methods: Using an experimental (post-test only) research design, participants (N = 97) were randomly assigned to one of four conditions, each providing a unique vignette. The experimental stimulus (i.e., vignettes) differed in terms of the intrinsic/extrinsic approach to sport injury therapy adopted by the athletes and their athletic therapist. After reading the vignette, each participant completed a series of items adapted from Wild et al. (1998) to measure athlete interest in therapy, positive behaviour change, therapist interest, and therapist efficacy. Results: Score reliability estimates varied considerably across experimental conditions (Mα = 0.69; SDα = 0.11). Athlete interest in therapy and positive behaviour change were highest when the athlete and athletic therapist were both intrinsically motivated (Pillai's Trace = 0.76, F(6, 186) = 19.12, p's < .01, partial eta-squared = 0.38). Therapist interest in working with the athlete in rehabilition and perceived therapist efficacy were highest when the athlete and athletic therapist were both intrinsically motivated (Pillai's Trace = 0.46, F(6, 186) = 9.31, p's < .01, partial eta-squared = 0.23). Discussion: Understanding the motivational basis for rehabiltation held by athletes and athletic therapists may play an important role in navigating the challenges of returning-to-sport competition following injury.