OBJECTIVE It has been suggested that the treatment of infant hydrocephalus results in different craniometric changes depending upon whether ventriculoperitoneal shunt (VPS) placement or endoscopic third ventriculostomy with choroid plexus cauterization (ETV/CPC) is performed. Without an objective and quantitative description of expected changes to the infant cranium and ventricles following ETV/CPC, asserting successful treatment of hydrocephalus is difficult. By comparing infants successfully treated via ETV/CPC or VPS surgery, the authors of this study aimed to define the expected postoperative cranial and ventricular alterations at the time of clinical follow-up. METHODS Patients who underwent successful treatment of hydrocephalus at 4 institutions with either VPS placement or ETV/CPC were matched in a 3:1 ratio on the basis of age and etiology. Commonly used cranial parameters (including head circumference [HC], HC z-score, fontanelle status, and frontooccipital horn ratio [FOHR]) were compared pre- and postoperatively between treatment cohorts. First, baseline preoperative values were compared to ensure cohort equivalence. Next, postoperative metrics, including the relative change in metrics, were compared between treatment groups using multivariate linear regression. RESULTS Across 4 institutions, 18 ETV/CPC-treated and 54 VPS-treated infants with hydrocephalus were matched and compared at 6 months postoperatively. The most common etiologies of hydrocephalus were myelomeningocele (61%), followed by congenital communicating hydrocephalus (17%), aqueductal stenosis (11%), and intraventricular hemorrhage (6%). The mean age at the time of CSF diversion was similar between ETV/CPC- and VPS-treated patients (3.4 vs 2.9 months; p = 0.69), as were all preoperative cranial hydrocephalus metrics (p > 0.05). Postoperatively, the ventricle size FOHR decreased significantly more following VPS surgery (-0.15) than following ETV/CPC (-0.02) (p < 0.001), yielding a lower postoperative FOHR in the VPS arm (0.42 vs 0.51; p = 0.01). The HC percentile was greater in the ETV/ CPC cohort than in the VPS-treated patients (76th vs 54th percentile; p = 0.046). A significant difference in the postoperative z-score was not observed. With both treatment modalities, a bulging fontanelle reliably normalized at last follow-up. CONCLUSIONS Clinical and radiographic parameters following successful treatment of hydrocephalus in infants differed between ETV/CPC and VPS treatment. At 6 months post-ETV/CPC, ventricle size remained unchanged, whereas VPS-treated ventricles decreased to a near-normal FOHR. The HC growth control between the procedures was similar, although the final HC percentile may be lower after VPS. The fontanelle remained a reliable indicator of success for both treatments. This study establishes expected cranial and ventricular parameters following ETV/CPC, which may be used to guide preoperative counseling and postoperative decision making.