© 2018 The Author(s). Background: There is an ever-increasing demand for widespread implementation of patient-reported outcomes. However, adoption is slow owing to limitations in clinical infrastructure and resources within busy orthopaedic practices. Prior studies showed the single alpha-numeric evaluation (SANE) score to correlate at a single point in time with the American Shoulder and Elbow Surgeons (ASES) score. However, no study has validated the SANE in terms of test-retest reliability, responsiveness, or clinical utility. Purpose: To validate SANE with the ASES across a sample of patients with common orthopaedic shoulder diagnoses. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Patients undergoing rotator cuff repair (n = 77), total shoulder replacement (n = 55), or physical therapy (n = 80) for signs and symptoms of subacromial impingement syndrome (n = 61) or adhesive capsulitis (n = 19) were administered the SANE and ASES at baseline and again at their 3-month follow-up from initial care or surgery (N = 212, mean ± SD age = 52.6 ± 1.2 years, n = 145 women). Interclass correlation coefficient (ICC2,1) and standard error of the measurement (SEm) were used to evaluate the test-retest reliability of the SANE and the validity between the SANE and ASES scores. Analysis of variance (treatment group × time) was used to evaluate the responsiveness to treatment, and a receiver operating characteristic curve was used to establish the minimal clinically important difference (MCID) for the SANE as compared with the ASES (α =.05). Floor and ceiling effects were evaluated as the percentage of patients who scored the highest or lowest score on each tool. Results: The SANE demonstrated good pretreatment reliability (ICC2,1 = 0.84, SEM = 3.8), similar to the ASES (ICC2,1 = 0.82, SEM = 3.4). The SANE also showed good agreement with the ASES before and after treatment across all treatment groups (rotator cuff repair, ICC2,1 = 0.85, SEM = 3.4; total shoulder replacement, ICC2,1 = 0.72, SEM = 5.2; physical therapy: ICC2,1 = 0.82, SEM = 2.9). The SANE and ASES displayed similar responsiveness after treatment, with similar mean change and SD within each treatment group. The receiver operating characteristic curve revealed an area under the curve of 0.79 (SE, 0.62; P <.001) and a cutoff of 15% on the SANE, with a sensitivity of 85% to establish the MCID. Acceptable and similar floor and ceiling effects were observed for the ASES (4%) and SANE (9%). Conclusion: The study demonstrates that the SANE is valid for a range of common shoulder diagnoses to assess patient outcomes across operative and nonoperative treatment for shoulder complaints. The MCID of 15% is similar to that of the ASES (11%), suggesting that the SANE is a simple and efficient tool to assess treatment effects for shoulder disorders. Future studies are warranted to confirm these results and compare across other body parts and diagnoses.