Adolescence is a rapid phase of human development at all levels—biologically, psychologically, and socially. The order of most of the biological changes appears to be universal, but the timing and the speed of changes may vary between individuals. During adolescence, important neuronal developments take place in regions of the brain such as the limbic system (which is associated with emotion regulation, reward processing, pleasure seeking, and sleep regulation) and the prefrontal cortex (which is associated with executive functions in late adolescence). Psychosocial and emotional changes occur in parallel with the hormonal and neurodevelopmental changes during adolescence. As their cognitive and intellectual capacities increase, adolescents develop reasoning skills, logic, and moral thinking. They also become more capable of abstract thinking and of making rational judgments. The changes that take place in the adolescent environment and the internal changes of adolescence are interrelated. External influences, which differ between cultures and societies, include social values and norms, as well as the changing roles, responsibilities, relationships, and expectations during this period of life. This entry discusses how culture shapes the experience of, and communication about, mental disorders in adolescence, as well as how it relates to the development of mental disorders.