Spinal deformity surgery represents one of the most challenging environments in which to achieve bone fusion. High rates of pseudarthroses, limited quantities of available autograft bone, and the potential morbidity of iliac crest harvest have driven a search for bone graft extenders and substitutes. With expanding knowledge of bone biology, the authors review options in spinal fusion with a particular focus on deformity surgery, including the use of autograft, allograft, demineralized bone matrix, ceramics, and bone morphogenetic proteins.