We performed a combined one-stage approach for the treatment of eighteen spastic subluxated or dislocated hips in eleven children who had cerebral palsy. All patients were between five and thirteen years old and had spastic subluxation or dislocation of the hip and severe acetabular dysplasia. The operation consisted of release of the adductors, psoas, and proximal hamstrings; a femoral-shortening varusderotation osteotomy; and a pericapsular pelvic osteotomy. The pelvic osteotomy was designed to increase superolateral coverage of the femoral head in the elongated acetabulum, which had erosion of the superior and lateral aspects. At the latest follow-up (mean duration, six years and ten months), seventeen of the eighteen hips remained anatomically reduced.