Screening for scoliosis at schools has become more and more popular despite the lack of knowledge concerning the clinical course of idiopathic scoliosis. An epidemiological study of 5303 schoolchildren showed three types of scoliosis in the community: (1) pelvic tilt scoliosis (an inconsequential deformity caused by an inequality in the length of the legs but accounting for almost 40% of curves detected); (2) spinal scoliosis (a minor asymmetry of the spine in the coronal plane that tends to remain static or to resolve and which may be normal in growing children, accounting for the remaining 60%); and (3) progressive scoliosis (10% of the spinal scolioses measuring 10 degrees or more that progress by 5 degrees or more a year). Progressive scoliosis resembles idiopathic scoliosis because in girls with right thoracic curves the potential for progression is appreciable. Until the natural history is better established growing awareness in the community of spinal deformity should help earlier detection, and screening should be directed towards providing subjects for further epidemiological work.