Adolescent athletes who sustain a musculoskeletal sports injury are at high re-injury risk. This prospective study evaluated athletic identity perception and fear avoidance perception relationships during the return to sport preparation phase of musculoskeletal injury rehabilitation. From 140 consecutive physical therapy outpatients, 50 (26 females, 24 males) adolescent athletes (mean age 16.8, range 14 to 22 y) completed the 7-item Athletic Identity Measurement Scale (AIMS), the 10-item Athletic Fear Avoidance Questionnaire (AFAQ), and the AFAQ with 2 additional movement-related fear and pain questions (AFAQ+). Correlational analysis was performed of overall AIMS and AIMS subscale scores (social identity, exclusivity, negative affectivity), with AFAQ and AFAQ+ scores ( P ≤0.05). Adolescent athletes were receiving treatment for musculoskeletal injuries sustained during soccer (n=10), lacrosse (n=7), baseball (n=6), basketball (n=5), volleyball (n=5), track or cross country (n=4), American football (n=4), field hockey or ice hockey (n=3), softball (n=2), tennis (n=2), and gymnastics (n=2). Lower extremity conditions included anterior cruciate ligament reconstruction (n=23) or other lower extremity conditions (n=17). Upper extremity conditions included shoulder dislocation or labral repair (n=6), elbow sprain or fracture (n=3), and clavicle fracture (n=1). The AIMS score displayed moderate inverse relationships with AFAQ ( r =-0.40, P =0.008) and AFAQ+ ( r =-0.41, P <0.004) scores. The "social identity" AIMS subscale score displayed a moderate inverse relationship with AFAQ ( r =- 0.48, P <0.001) and AFAQ+ ( r =-0.46, P =0.001) scores. The "exclusivity" AIMS subscale score displayed moderate inverse relationships with AFAQ ( r =-0.40, P =0.005) and AFAQ+ ( r =-0.46, P =0.001) scores. The "negative affectivity" subscale did not display significant relationships with AFAQ or AFAQ+ scores. Subject age displayed moderate inverse relationships with the AIMS "social identity" ( r =-0.56, P <0.001) and "exclusivity" ( r =-0.42, P =0.004) subscale scores and weak direct relationships with AFAQ (r=0.30, P =0.04) and AFAQ+ (r=0.32, P =0.02) scores. Adolescent athletes with stronger athletic identity perceptions during the return to the sports preparation phase of musculoskeletal injury rehabilitation had weaker fear avoidance perceptions. As age increased from early to late adolescence, athletic identity perceptions became weaker, and fear avoidance perceptions became stronger. To decrease re-injury rates, early identification and surveillance of injured adolescent athletes with stronger, more exclusive athletic identity perceptions and weaker fear avoidance perceptions may influence rehabilitation progression and return to play decisions. Level-II, prospective cohort, correlational study.