Atraumatic shoulder pain is frequently encountered in primary care and surgical clinics. With increased recognition of the biopsychosocial model, there has been an increased emphasis on identifying patient factors associated with less effective coping strategies such as pain catastrophizing. It remains uncertain what impact self-efficacy has on the response to nonoperative treatment of shoulder pain. Our purpose is to determine the influence of patient coping strategies (self-efficacy) on the outcome of nonoperative treatment of atraumatic shoulder pain. We hypothesize that higher levels of self-efficacy are associated with increased self-reported function after nonoperative treatment. We conducted a retrospective case-control study for a consecutive series of patients seen in our clinic with nonoperatively managed atraumatic shoulder pain. Baseline demographics and range of motion were recorded. Patients completed the Simple Shoulder Test (SST), PROMIS Pain Interference (PI), and PROMIS Self-Efficacy for Managing Symptoms (SE). After 3months of nonoperative treatment, patients were placed into two groups: patients who clinically improved (Group 1) and those that did not (Group 2), with clinical improvement defined as an increase of 2 or greater on the SST. Seventy-eight patients returned for follow-up and completed all questionnaires. There were no statistically significant differences for age, sex, or tobacco use between the two groups. Half of the patients in our series had symptoms for >12months, with rotator cuff syndrome being the most frequent diagnosis (40.0%). Patients in Group 1 had significantly higher PROMIS SE scores (42 vs. 39, p=0.0094) at initial evaluation. At 3-month follow-up, patients in Group 1 also had significantly lower Numeric Pain Rating Scale (NPRS) scores (4.5 vs. 6.5, p=0.0067), compared to Group 2. Patients who experience clinical improvement with nonoperative treatment of atraumatic shoulder conditions demonstrate higher self-efficacy than patients who fail to improve. Guiding patients with atraumatic shoulder pain and low self-efficacy toward interventions aimed at improving coping strategies, rather than addressing musculoskeletal factors alone, may contribute to the goal of improving outcomes.