Dr. Khan is a Resident, Department of Orthopaedic Surgery, the University of California, Davis, Davis, CA. Dr. Cammisa is Chief, Spinal Surgical Service, Hospital for Special Surgery, New York, NY. Dr. Sandhu is Associate Attending Surgeon and Director, Spine Surgery Fellowship Program, Hospital for Special Surgery, New York. Dr. Diwan is Chief and Director, Spine Service and Fellowship Program, Department of Orthopedic Surgery, St. George’s Hospital, University of New South Wales, Sydney, Australia. Dr. Girardi is Assistant Attending Surgeon, Hospital for Special Surgery, New York. Dr. Lane is Attending Surgeon and Director, Metabolic Bone Disease Service, Hospital for Special Surgery, New York. Reprint requests: Dr. Sandhu, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021. Many approaches are used to repair skeletal defects in reconstructive orthopaedic surgery, and bone grafting is involved in virtually every procedure. The type of bone graft used depends on the clinical scenario and the anticipated final outcome. Autogenous cancellous bone graft, with its osteogenic, osteoinductive, and osteoconductive properties, remains the standard for grafting. However, the high incidence of morbidity during autogenous graft harvest may make the acquisition of grafts from other sources desirable. The clinical applications for each type of bone graft are dictated by the structure and biochemical properties of the graft. An elegant cellular and molecular cascade follows bone transplantation. Bone graft incorporation within the host, whether autogenous or allogeneic, depends on many factors: type of graft (autogenous versus allogeneic, vascular versus nonvascular), site of transplant, quality of transplanted bone and host bone, host bed preparation, preservation techniques, systemic and local disease, and mechanical properties of the graft.