Cranial deformation is the most common cause of abnormal head shape. Intentional and unintentional alterations of cranial form are associated with the application of external pressure to the growing infant head, and such changes have been recorded throughout man's history. Recent changes in Western sleeping practices, instituted to reduce the incidence of sudden infant death syndrome, have led to a dramatic rise in the incidence of cranial deformation and renewed interest in this subject. This 2-part review presents a pragmatic clinical approach to this topic including a critical review of the literature as it applies to each aspect of this common diagnosis: historical perspective, terminology, differential diagnosis, etiopathogenesis and predisposing factors, and prevention and treatment.