Stress relaxation and static progressive stretch (SPS) are techniques that may be used to nonoperatively restore joint range of motion in the setting of adhesive capsulitis. The purpose of this study was to prospectively compare standard physical therapy alone to a combination of physical therapy with a static progressive stretch orthosis in the treatment of shoulder adhesive capsulitis. A prospective, randomized, blinded, controlled study was conducted with a total of 60 patients diagnosed with shoulder adhesive capsulitis (30 patients in the control group, 30 patients in the treatment group). The control group received physical therapy for 4 weeks, while the experimental group received physical therapy and were treated with a static progressive stretch shoulder device for 4 weeks. Active and passive abduction, passive external rotation, DASH scores, and VAS pain scores were recorded for all patients at 4, 12, and 24 weeks follow-up. Use of a static progressive stretch orthosis compared to physical therapy alone demonstrated a significantly greater mean improvement in all range-of-motion categories. Mean passive abduction was 162° with the orthosis versus 136° with physical therapy alone. Mean active abduction was 141° and 114°, respectively. Mean external rotation was 73° and 52°, respectively. DASH scores were significantly better when a static progression stretch orthosis was used (5 vs.15 points). Use of a static progressive stretch orthosis for patients with shoulder adhesive capsulities resulted in significantly better range of motion and DASH scores within 1 month of beginning treatment than physical therapy alone.