© 2018 Elsevier Inc. Congenital hydrocephalus (CH), featuring markedly enlarged brain ventricles, is thought to arise from failed cerebrospinal fluid (CSF) homeostasis and is treated with lifelong surgical CSF shunting with substantial morbidity. CH pathogenesis is poorly understood. Exome sequencing of 125 CH trios and 52 additional probands identified three genes with significant burden of rare damaging de novo or transmitted mutations: TRIM71 (p = 2.15 × 10−7), SMARCC1 (p = 8.15 × 10−10), and PTCH1 (p = 1.06 × 10−6). Additionally, two de novo duplications were identified at the SHH locus, encoding the PTCH1 ligand (p = 1.2 × 10−4). Together, these probands account for ∼10% of studied cases. Strikingly, all four genes are required for neural tube development and regulate ventricular zone neural stem cell fate. These results implicate impaired neurogenesis (rather than active CSF accumulation) in the pathogenesis of a subset of CH patients, with potential diagnostic, prognostic, and therapeutic ramifications. Congenital hydrocephalus (CH) is a major cause of childhood morbidity and mortality, affecting 1 in 1,000 live births and representing up to 3% of all pediatric hospital charges. Using data from the largest CH exome sequencing study to date, Furey et al. identify four genes (TRIM71, SMARCC1, PTCH1, and SHH) not previously implicated in CH. Remarkably, all four genes regulate ventricular zone neural stem cell fate and, together, explain ∼10% of CH cases. These findings implicate impaired neurogenesis in pathogenesis of a significant number of CH patients, with potential diagnostic, prognostic, and therapeutic ramifications.