The goal of this study was to compare the Oxford Shoulder Score (OSS), the Shoulder Pain and Disability Index (SPADI), and the Short Form 36 (SF-36) for their correlation, agreement, sensitivity to change, and test-retest reliability in patients with a clinical diagnosis of subacromial impingement. All patients attending a specialist subacromial impingement clinic over a 6-month period completed the OSS, SPADI, and SF-36 at each visit. A total of 323 sets of observations were recorded in 110 patients. The first 38 of these patients were also sent the questionnaires to complete before their visit. There was good correlation between the OSS and SPADI scores (correlation coefficient = 0.85) and good agreement between the scores on each scale (weighted kappa = 0.79). The correlation with total SF-36 was poor (0.37 for OSS and 0.26 for SPADI). The OSS and SPADI showed good effect sizes compared with the total SF-36 score and good test-retest reliability. These data support the use of the OSS or SPADI in patients with subacromial impingement.