To develop and test a socio-medical index of health (referred to as the Nottingham Health Index). This index aims to provide a measurement of a person's need for care beyond purely `medical' aspects (as indicated by physiological or biochemical measurements): it measures a person's functioning in physical, social and emotional terms. Variables Various versions of the Nottingham Health index were used in the study of: 1) all cases admitted to a Government Employment Rehabilitation Centre between 26th August 1976 and 8th January 1977; 2) all patients referred to a clinic at the City Hospital, Nottingham, between August 1976 and May 1977 suffering from cervical spondylosis or frozen shoulder; 3) Patients under the care of a senior orthopaedic surgeon concerned with hip-replacement operations; 4) all patients suffering from arthritic hip or knee conditions attending the orthopaedic out-patient clinics over a period of 4 weeks; 5) A one in four sample of patients seen by the doctor in three general practice surgeries in the Nottinghamshire area over a three week period.