Currently, there are changes in the mental and somatic state of children that go beyond the limits of classical concepts. Significant changes are also taking place in the education system. All this makes it necessary to revise approaches to the analysis of deviant development.After analyzing the existing models and approaches to the typology of mental development, the authors propose a modern three-component model of analysis, on the basis of which a new typology is built. The book provides a detailed description of the distinguished types of deviant development, describes a diagnostic procedure that allows you to determine the nature of deviations, predict the further development of the child, competently plan corrective work, and choose the best educational route for the child.The book is addressed primarily to psychologists -practitioners working in the field of special and clinical psychology of childhood, specialists in the psychological and pedagogical support of children with deviant development in educational systems. In addition, it will be of interest to educators and clinicians, including neurologists, psychiatrists, pediatricians, and other healthcare professionals.