Craniosynostosis is a defect of the skull caused by early fusion of one or more of the cranial sutures and affects 3 to 5 individuals per 10,000 live births. Craniosynostosis can be divided into two main groups: syndromic and nonsyndromic. Nonsyndromic craniosynostosis is typically an isolated finding that is classified according to the suture(s) involved. Syndromic craniosynostosis is associated with various dysmorphisms involving the face, skeleton, nervous system, and other anomalies and is usually accompanied by developmental delay. More than 180 syndromes exist that contain craniosynostosis. Secondary effects of craniosynostosis may include vision problems and increased intracranial pressure, among others. The molecular basis of many types of syndromic craniosynostosis is known, and diagnostic testing strategies will often lead to a specific diagnosis.