The number of cases diagnosed with developmental disorders is rapidly increasing among those consulting psychiatry clinics for the first time in their adulthood. The author presents the concept of developmental disorders, discusses how they can be differentiated from other psychiatric disorders, and proposes some treatments. From now on, all psychiatrists should know the difference between developmental disorders and other psychiatric disorders, and diagnose them multi-axially, including the dimension of development. They should always keep in mind how developmental disorders lead to difficulties in everyday life, and treat developmental disorders in conjunction with adequate environmental modifications along with the treatment of other comorbid psychiatric disorders.
 <Author's abstract>