Shoulder disorders, including rotator cuff disease (tendinopathy, impingement, subacromial bursitis, tears), adhesive capsulitis, instability, glenohumeral osteoarthritis, dislocation, proximal humeral or humeral head fractures, and unspecified shoulder pain, are highly prevalent disorders (7–26%), and are associated with significant morbidity, disability, and economic burden. Despite increasing numbers of trials investigating the benefits and harms of treatments for these disorders, there is as yet no widely endorsed core domain set (for outcome domains) or core outcome measurement set (for instruments) that is advocated for clinical trials. The Outcome Measures in Rheumatology (OMERACT) Shoulder Working Group was established in 2015 to develop these sets for clinical trials of shoulder disorders addressing all types of interventions.