Allograft use continues to be important in modern spinal surgery due to its abundant supply, ability to customize to shape, and avoidance of donor site morbidity. However, surgeons must be aware of the limitations of the grafts when used in isolation and how to obtain bony healing. These limitations include subsidence from altered mechanical properties, a lack of osteoinduction and risk of immunogenicity. Optimal healing can be achieved through optimizing the host, selecting the correct graft for the bony environment where the healing is required, and optimizing local graft site biology and stability. Tissue engineering in arthrodesis through obtaining a stable mechanical construct, use of an appropriate structural allograft, and placement of a biologic component (e.g., BMP-2) has shown to be a reliable means to obtain union and achieved satisfactory outcomes. Novel biological agents show promise and will continue to mature in their clinical application.