The choice of treatment for osteonecrosis of the femoral head should be based primarily on the stage of the lesion. Patient-related factors also influence treatment alternatives. The extent of an osteonecrotic lesion of the hip can be determined predominantly from radiographic findings. The authors primarily use four parameters: presence of collapse, lesion size, extent of head depression, and acetabular involvement. In smaller precollapse lesions, nonoperative pharmacologic methods and core decompression may do well. Bone grafting, both vascularized and nonvascularized, may have better results in larger precollapse and early postcollapse lesions. Limited femoral resurfacing has a role in postcollapse lesions in which the acetabular cartilage is preserved. Total hip arthroplasty is the only treatment for lesions with extensive acetabular involvement. A treatment algorithm is presented.