Depression belongs to the most common mental disorders of young people. Yet, its analysis has given rise to many controversies among specialists. One of the crucial raised issues is the question whether it is justified to apply the diagnosis of depression in this age group, considering the fact that intrapsychic mechanisms in adolescents are not yet mature. The theoretical problem arises: to what degree adolescent depression ought to be considered a clinical disorder, rather than a specific developmental reaction. In the present paper, the attempt has been undertaken to tackle the issue. It has been found that the diagnosis of adolescent depression cannot rely on clear-cut diagnostic criteria. Instead, it should rely on clinical assessment of an individual patient.