Currently, changes in the mental and somatic state of children are observed that go beyond classical ideas. Significant changes are also taking place in the education system. All this calls for a need to revise approaches to the analysis of deviant development. Having analyzed 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 identified types of deviant development, describes a diagnostic procedure that allows you to determine the nature of the deviations, predict the further development of the child, competently organize correctional work, and choose the optimal educational route for the child. The book is addressed primarily to practicing psychologists working in the field of special education. and clinical childhood psychology, specialists in psychological and pedagogical support for children with developmental disabilities in educational systems. In addition, it will be of interest to teachers and clinicians, including neurologists, psychiatrists, pediatricians, and other health care professionals.