Adult degenerative lumbar scoliosis is a three-dimensional deformity occurring de novo secondary to asymmetric degeneration of the adult spine. It is a debilitating condition increasingly encountered by spine surgeons as the elderly population continues to grow. The deformity is progressive and patients often present later in life with disability and comorbidities. Several classification systems have been developed, and some have evolved to predict outcomes and guide surgical treatment. Conservative management should always be initially pursued but has limited utility for definitive treatment. Many of these patients go on to require a surgical intervention which often involves long-segment fusions with correction of the deformity and appropriate decompression of the neural elements. Recent advancements in implants and techniques combined with growing literature on the topic have led to the ability to obtain greater correction of patients’ deformities, although these may also increase the risk of mechanical and junctional complications. This chapter will discuss adult degenerative lumbar scoliosis and provide updated information for different facets of this increasingly common spinal pathology.