Puberty and adolescence are not generally times of great stress and turmoil. The storm-and-stress theory has a long history, but can no longer be supported by recent empirical research. A modern approach to the psychosocial changes of these phases is based on the concept of developmental tasks in an age-appropriate and stage-appropriate way. Biological processes can influence an individual’s psychological and psychosocial state, but psychological and psychosocial events may also influence the biological systems. Therefore, the timing and outcome of pubertal processes can be modified by psychosocial factors. The most important psychological and psychosocial changes in puberty and early adolescence are the emergence of abstract thinking, the growing ability of absorbing the perspectives or viewpoints of others, an increased ability of introspection, the development of personal and sexual identity, the establishment of a system of values, increasing autonomy from family and more personal independence, greater importance of peer relationships of sometimes subcultural quality, and the emergence of skills and coping strategies to overcome problems and crises. All these changes can be looked on as developmental tasks during normal development, but they can also help in understanding developmental deviations and psychopathological disorders. From the viewpoint of developmental psychopathology, several psychiatric disorders of puberty and adolescence can be seen in a new light.