Chronic shoulder pain is a frequently reported phenomenon in individuals who use wheelchairs as their primary means of mobility. No indices are currently available which detect difficulties in performing daily activities due to shoulder discomfort in a largely independent population of wheelchair users. The Wheelchair User's Shoulder Pain Index (WUSPI) was designed to measure shoulder pain in individuals who use wheelchairs. A pilot index was created to measure shoulder pain and related difficulty during basic and instrumental activities of daily living. The instrument was administered to 64 wheelchair users at an athletic event. Analyses of internal consistency and interitem correlations were used to revise and refine the original instrument. Individual item analysis revealed that the subjects in this study experienced the most shoulder pain when wheeling up an incline or on outdoor surfaces, when lifting an object from an overhead shelf, when trying to sleep, when transferring from tub to wheelchair and when washing their backs. The final 15-item index shows high internal consistency. This instrument is useful for both clinical and research purposes to detect and monitor shoulder pain and accompanying loss of function by wheelchair users.