The irritability is very frequent on children remitted to institutions from Health juvenile mental illness and can be a source of severe psychosocial disabilities. However, irritability is also part of the human experience normal. The apparent tension Come in they ha been object from a large debate in psychiatry for some time, but has also stimulated the scientific research on irritability as a mental state. East chapter gathers knowledge scientists and clinical from various sources for to help to the doctors to understand the origin and the driving from the state from cheer up irritable on children and teenagers.