The Hydrocephalus Clinical Research Network (HCRN) has been established by philanthropic funding to conduct multi-institutional research (clinical trials and observational studies) on pediatric hydrocephalus. The HCRN consists of four Clinical Centers and the Data Coordinating Center (DCC). The HCRN Core Data Project will obtain data about all neurosurgical hydrocephalus events from the network Clinical Centers, and create a database to be used by HCRN investigators. The ongoing maintenance of the Core Data Project serves two main purposes: (1) ) it will help investigators understand the variability, progression, and current treatment practices for hydrocephalus in children, with an ultimate goal of better guiding and assessing therapeutic intervention and providing recommendations on patient care and; (2 it will provide pilot and descriptive data necessary for hypothesis generation and study design (i.e. preliminary power analyses, recruitment projections) for studies under development by the HCRN This multi-institutional database will be maintained throughout the lifetime of the HCRN, and may be useful for tracking trends in pediatric hydrocephalus over time. The Core Data Project will be an invaluable resource to the HCRN and will help stimulate new research protocols, identify potential need for future expansion of the network to incorporate additional patient populations, and provide a descriptive understanding of children with hydrocephalus cared for within the network.