One approach to the study of language has been to describe people whose ability to communicate is impaired. Some researchers have argued that it is possible to identify the component mental processes that contribute to the ability to communicate by describing the ways in which language can break down. Other researchers have expressed doubts about the extent to which data from impairment reflects normal language function. This volume reflects the problems of constructing theory of how the normal brain deals with language from data from impaired individuals from the perspective of a range of disciplines: psycholinguistics, linguistics, neurophysiology and speech-language pathology. The chapters include critiques of methodology; application of new technology; the study of bilingual people; and cross-linguistic studies. A range of language skills is discussed (phonology, prosody, syntax, semantics, reading and spelling) in the context of both developmental and acquired impairments (hearing loss, cerebellar dysarthria, sub-cortical aphasia, cortical aphasia, phonological disorder, and dyslexia). This book icludes contributions from researchers and clinicians on both sides of the Atlantic as well as from Australia and Hong Kong.