This book offers a comprehensive and readable account of theoretical aspects of the origins and normal development of handedness and its relationship to cerebral lateralization. It reviews the evidence for links between non-right-handedness and various developmental disorders: mental impairment, autism, epilepsy, and disorders of spoken and written language. The emphasis is on understanding the range of underlying mechanisms that might lead to associations between handedness and disorder and on identifying assessment procedures that can distinguish between different explanations.