The natural history presented in this chapter applies only to AIS. Other types of scoliosis have their own natural history and associated problems that may significantly affect the ability of the patient to meet the demands of daily life. Increased public awareness and screening clinics have resulted in an increased number of children referred for orthopaedic opinion, less severe curve magnitude at initial detection, and earlier institution of treatment. Treatment of each patient must be individualized, taking into consideration the probability of curve progression based on curve magnitude, skeletal maturity, sexual maturity, and age (Table 6-7). Overdiagnosis and unnecessary treatment must be avoided. As our knowledge of the natural history of AIS expands, treatment decisions can be based on objective rather than subjective data. Any proposed treatment of this condition must have a reasonable chance of altering the natural history in a positive way. The information available on natural history has been accumulated on relatively small groups of patients and the conclusions presented represent generalities. There are probably many "natural histories" for AIS, especially with reference to curve progression; therefore, treatment decisions must be individualized. Long-term results of various treatments for scoliosis must take into consideration the natural history of the disorder.