Hip subluxation occurs frequently in children with severe cerebral palsy. This retrospective study examined the effects of age and type of bony surgery on radiographic outcomes of children with severe cerebral palsy who were treated for hip subluxation. The study included nonambulatory children with cerebral palsy undergoing bony hip reconstructive surgery consisting of proximal femoral varus derotational osteotomy (VDRO) alone or combined with pelvic osteotomy. The migration index was recorded for preoperative, postoperative, and final follow-up (minimum 2 years) radiographs. Failure was defined as subsequent bony hip reconstructive surgery or final follow-up migration index greater than 50%. Seventy-seven hips in 40 patients younger than 6 years (55 VDRO alone, 22 combined) and 73 hips in 43 patients older than 6 years (27 VDRO alone, 46 combined) met inclusion criteria. For VDRO alone, the failure rate for patients younger than 6 years (33%) was significantly higher than for patients older than 6 years (7%). For combined procedures, failure rates between younger (0%) and older groups (9%) were not significantly different. Patients younger than 6 years undergoing combined procedures started with a significantly worse migration index than patients undergoing VDRO alone, 72% vs 46%, yet had significantly better final migration indices of 13% vs 31%, respectively. For surgeons performing bony reconstructive surgery to treat hip subluxation in younger children with severe cerebral palsy who are nonambulatory, the findings of this study support the use of combined VDRO and pelvic osteotomy. [Orthopedics. 2021;44(2):e294-e300.].