Stiffness is a consistent but nonspecific symptom of primary frozen shoulder, a condition defined by restriction of passive motion in all planes without glenohumeral abnormalities on plain radiographs. Since the first description by Duplay in 1872, theories and descriptions of the lesions have varied over time and across authors, with the main target of the condition being reported as the subacromial bursa in some studies and the rotator interval in others. Recent publications have pointed out similarities with Dupuytren's contracture. Magnetic resonance imaging has helped to understand the lesions by showing a specific pattern of postgadolinium enhancement during the first few months after symptom onset. Pain relief is the main objective of therapy. Oral medications have not been adequately evaluated, with the exception of glucocorticoids, which hasten the resolution of nighttime pain to a modest degree. Intra-articular glucocorticoid injections are effective and are best performed under arthrographic control. It has been suggested that intra-articular glucocorticoid injections should be combined with joint capsule distension. An additional injection into the subacromial bursa has been found useful in patients with refractory pain. Motion range recovery is not always complete after 18 to 24 months and can be improved by physiotherapy. Methodological difficulties have precluded demonstration in formal studies of the undeniable benefits of physiotherapy. Joint capsule distension, and even more so arthroscopic capsulotomy with gentle mobilization, have provided promising results in patients with persistent stiffness, although the optimal time for performing these techniques remains to be determined.