How independent are different cognitive skills during development? Is the modularity seen in the studies of adult neuropsychology disorders mirrored by modularity in development? Are developmental neuropsychological disorders explicable against cognitive models? What restrictions are there to developmental plasticity? How many routes are there to competence? Is there a single developmental pathway? What do disorders of cognitive development tell us about normal developmental processes? These are some of the questions addressed by this text.In certain cognitive domains, such as the analysis of reading and spelling disorders, the field is well developed, with extensive studies of the development of dyslexias and dysgraphias. In other areas, such as the analysis of perceptual spatial disorders, pertinant studies are beginning, as in the analysis of developmental face recognition disorders, and the exploration of spatial disorders of Williams' syndrome. In these areas, interesting routes for future inquiry are also evident. The text of this book is organized around seven key cognitive areas, within which the developmental disorders are addressed in turn: language, memory, perception, reading, spelling, arithmetic and executive skills. The first three of this list may be considered the core areas of cognition; the second three involve specific cultural transmission in their acquisition; and the third, concerns higher order processes. The major emphasis of the text is upon developmental rather than acquired disorders. Throughout, case studies are used to convey an impression of the cases themselves, and to illustrate how dissociations in performance are displayed.