© AANS 2018. OBJECTIVE: High-quality data comparing endoscopic third ventriculostomy (ETV) with choroid plexus cauterization (CPC) to shunt and ETV alone in North America are greatly lacking. To address this, the Hydrocephalus Clinical Research Network (HCRN) conducted a prospective study of ETV+CPC in infants. Here, these prospective data are presented and compared to prospectively collected data from a historical cohort of infants treated with shunt or ETV alone. METHODS: From June 2014 to September 2015, infants (corrected age ≤ 24 months) requiring treatment for hydrocephalus with anatomy suitable for ETV+CPC were entered into a prospective study at 9 HCRN centers. The rate of procedural failure (i.e., the need for repeat hydrocephalus surgery, hydrocephalus-related death, or major postoperative neurological deficit) was determined. These data were compared with a cohort of similar infants who were treated with either a shunt (n = 969) or ETV alone (n = 74) by creating matched pairs on the basis of age and etiology. These data were obtained from the existing prospective HCRN Core Data Project. All patients were observed for at least 6 months. RESULTS: A total of 118 infants underwent ETV+CPC (median corrected age 1.3 months; common etiologies including myelomeningocele [30.5%], intraventricular hemorrhage of prematurity [22.9%], and aqueductal stenosis [21.2%]). The 6-month success rate was 36%. The most common complications included seizures (5.1%) and CSF leak (3.4%). Important predictors of treatment success in the survival regression model included older age (p = 0.002), smaller preoperative ventricle size (p = 0.009), and greater degree of CPC (p = 0.02). The matching algorithm resulted in 112 matched pairs for ETV+CPC versus shunt alone and 34 matched pairs for ETV+CPC versus ETV alone. ETV+CPC was found to have significantly higher failure rate than shunt placement (p < 0.001). Although ETV+CPC had a similar failure rate compared with ETV alone (p = 0.73), the matched pairs included mostly infants with aqueductal stenosis and miscellaneous other etiologies but very few patients with intraventricular hemorrhage of prematurity. CONCLUSIONS: Within a large and broad cohort of North American infants, our data show that overall ETV+CPC appears to have a higher failure rate than shunt alone. Although the ETV+CPC results were similar to ETV alone, this comparison was limited by the small sample size and skewed etiological distribution. Within the ETV+CPC group, greater extent of CPC was associated with treatment success, thereby suggesting that there are subgroups who might benefit from the addition of CPC. Further work will focus on identifying these subgroups.