A newborn's skull is highly malleable and rapidly expanding. As a result, any restrictive or constrictive forces applied to a baby's head can result in dramatic distortions. These changes can be mild, reversible deformations or severe, irreversible malformations that can result in brain injury. This paper reviews the anatomy and physiology of normal and abnormal brain and skull growth, the etiology of cranial deformation, the types of craniosynostosis most commonly seen in infants, and the importance of early diagnosis and treatment.