Patient-reported outcomes (PROs) are frequently utilized within orthopaedics to determine the extent of patient disease and the efficacy of surgical treatments. Shoulder arthroplasty is a common treatment option for a range of pathologies; however, substantial variety exists regarding the instruments used within the published literature, limiting their quality and generalizability. The purpose of the present systematic review is to evaluate the overall number and frequency of outcome measures used in all clinical studies evaluating outcomes following shoulder arthroplasty. This systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Relevant studies that assessed patient reported outcomes following total shoulder arthroplasty, reverse shoulder arthroplasty, and shoulder hemiarthroplasty were obtained from PubMed, MEDLINE, and EMBASE databases. For each manuscript, the journal, authors, region of origin, level of evidence, and subject/pathology were recorded. The frequency of each reported outcome measure and category. Associations between study characteristics and measure categories were tested using Poisson regression with robust error variance. A total of 682 articles were included in the analysis, reporting 42 different PROs. The most popular tools were the Constant-Murley score (49.7%), the American Shoulder and Elbow Surgeons Evaluation Form (37.7%), and the Visual Analog Scale (34.3%). A generic outcome tool was used in 287 studies (42.1%), while 645 (94.6%) utilized a shoulder-specific measure and 49 (7.2%) used a disease-specific measure. The use of generic (p<0.001) and disease specific (p<0.001) measures were associated with higher level of evidence. Studies assessing patient outcomes following shoulder arthroplasty employ a large range of PRO measuring tools, many of which are non-validated. Furthermore, only a small percentage of studies utilize a combination of tools from different categories despite current recommendations. Consensus on validated and clinically-meaningful tools from multiple categories is necessary to increase the generalizability and applicability of published studies in shoulder arthroplasty literature. 1.