The members of the Upper Extremity Committee of ISAKOS meet in Amsterdam in May 2014 with the aim to create a consensus statement on the definition, classification and treatment of the stiff shoulder. The committee recommended that the term “stiff shoulder” is used to describe the patient who presents with a restricted range of motion and that the aetiology can be due to primary or secondary causes. The term “frozen shoulder” is to be used exclusively for idiopathic stiff shoulder and “secondary stiff shoulder” for those cases with a known aetiology. We do not recommend the use of the term adhesive capsulitis. The committee recommends that the stiff shoulder be classified as intra-articular (cartilage and synovium), capsular and extra-articular. The extra-articular components include the rotator cuff muscle and tendon, but also factors remote to the joint such as heterotopic ossification, burns contracture and neurological causes. The “shoulder machine” is described with its neurological control, the motor and the articular components of the joint. The stiff shoulder is due to the pathoanatomical consequences of the primary insult, pathological response and secondary insult.