This book reviews our knowledge of the incoherent speech which can present as a symptom of schizophrenia. This is one of the most researched symptoms in the disorder. The content covers clinical presentation, differential diagnosis and the theories proposed to account for the symptom in these 'thought disordered' patients, ranging from the psychoanalytic to there being a form of aphasia involved. The book is unique in its ability to apply linguistic and neuropsychological approaches to the understanding of this condition, and is the first book to cover comprehensively the range of clinical studies that followed the introduction of Andreasen's rating scale for what was then called thought, language and communication disorder. This book is essential reading for all those working in the field of schizophrenia and also for those interested in language and disorders of speech.