Growth of the skull vault is closely coordinated with expansion of the underlying brain and primarily occurs at cranial sutures. These are the narrow strips of fibrous mesenchyme separating the flat bones of the skull vault that contain a population of cells with the capacity to respond to changes in brain volume and control bone deposition at the sutural margins. Sutures fuse naturally after full brain size is achieved, but in approximately 1 in 2,250 children fusion occurs prematurely during fetal development or infancy. This is called craniosynostosis and it has potentially serious consequences for brain development and can lead to problems with vision, hearing, breathing and dentition. To understand why this happens our approach has been to identify underlying genetic causes. As well as providing invaluable information for patients and families, this has shed light on the embryological processes important for cranial suture development.