This chapter describes the adolescent idiopathic scoliosis (AIS). Scoliosis is a three-dimensional deformity with lateral deviation and torsion of the vertebrae. Discs and facets, platelet abnormalities, the slender column theory, endocrinological, neurodevelopmental and melatonin are the etiology of AIS. The prevalence of AIS by school screening program is 0.3–15.3%. This varies with the curve magnitude and the population studied. Sex, remaining growth, curve magnitude and curve pattern are the different factors predicting the progression of AIS. Various treatment modalities are adopted over years to treat AIS. But, many of them like manipulation, physical therapy, etc. 36 well-colored figures are also provided in this chapter. Two well-illustrated and well-colored flow charts are on bracing course and algorithm for management of neurovascular injury are also provided in this chapter.