OBJECTIVE Infants with severe hydrocephalus and extreme macrocephaly typically undergo CSF diversion early in life, which can result in significant cranial deformity due to CSF overdrainage. In this scenario, overlap of the cranial plates can precede the development of secondary synostosis and/or severe, permanent cranial deformity. As a result, extensive cranial vault remodeling is sometimes undertaken later in life, which is often challenging and has been associated with mortality and a high morbidity rate. The authors have previously described a technique for early postnatal cranial vault reduction and fixation (CVRF), in which the calvarial bones are stabilized using absorbable fixation plates in the neonatal period, in an attempt to facilitate patient positioning, simplify hydrocephalus management, and improve cosmesis. Here, the authors describe their institutional experience managing patients with extreme neonatal hydrocephalus with CSF diversion, with and without CVRF, over the past 12 years. METHODS The authors retrospectively reviewed the charts of infants with extreme hydrocephalus (head circumference > 49 cm) treated at their children's hospital with ventriculoperitoneal shunting, with or without CVRF, between 2005 and 2017. Data collected included age, sex, etiology of hydrocephalus, type of CVRF performed (anterior, posterior, or combined), follow-up duration, orbitofrontal circumference, craniometric measurements, intraoperative blood loss, operative duration, and postoperative complications. Developmental data were collected using the third edition of the Ages and Stages Questionnaire. Photographic imaging was used to demonstrate esthetic outcomes, and family questionnaires were used to evaluate satisfaction with the esthetic outcome. RESULTS Eleven patients with extreme neonatal hydrocephalus underwent CSF shunting; 5 underwent shunting alone and 6 patients underwent shunting and CVRF. For patients who underwent shunting and CVRF, the median age at CVRF was 6 days and the median interval between shunt placement and CVRF was 2.5 days. The mean extent of calvarial vault volume reduction was 44.5% (± 3.9%). The mean duration of the CVRF procedure was 108 minutes, and 5 of 6 patients required intraoperative transfusion. Of the 5 patients who underwent shunting alone, 3 developed severe cranial deformities. Of 6 patients who underwent shunting and CVRF, 1 had a poor cosmetic outcome. In the shunting-alone group, 2 patients died and 1 required extensive cranial vault correction at 10 years of age. One patient in the shunting and CVRF group also died. CONCLUSIONS CVRF in combination with CSF shunting in the neonatal period can simplify the treatment of the rare case of severe hydrocephalic macrocephaly and leads to cosmetic outcomes that are considered good by their families.