Many terms are used to describe emotional, behavioral or mental disorders. Currently, students with such disorders are categorized as having an emotional disturbance, which is defined under the Individuals with Disabilities Education Act as follows:
"...a condition exhibiting one or more of the following characteristics over a long period of time and to a marked degree that adversely affects a child's educational performance--
(A) An inability to learn that cannot be explained by intellectual, sensory, or health factors.

(B) An inability to build or maintain satisfactory interpersonal relationships with peers and teachers.

(C) Inappropriate types of behavior or feelings under normal circumstances.

(D) A general pervasive mood of unhappiness or depression.

(E) A tendency to develop physical symptoms or fears associated with personal or school problems." [Code of Federal Regulations, Title 34, Section 300.7(c)(4)(i)]

As defined by the IDEA, emotional disturbance includes schizophrenia but does not apply to children who are socially maladjusted, unless it is determined that they have an emotional disturbance. [Code of Federal Regulation, Title 34, Section 300.7(c)(4)(ii)]
Incidence

In the 2000-2001 school year, 473,663 children and youth with an emotional disturbance were provided special education and related services in the public schools (Twenty-fourth Annual Report to Congress, U.S. Department of Education, 2002).
Characteristics

The causes of emotional disturbance have not been adequately determined. Although various factors such as heredity, brain disorder, diet, stress, and family functioning have been suggested as possible causes, research has not shown any of these factors to be the direct cause of behavior or emotional problems. Some of the characteristics and behaviors seen in children who have emotional disturbances include:
Hyperactivity (short attention span, impulsiveness);
Aggression/self-injurious behavior (acting out, fighting);
Withdrawal (failure to initiate interaction with others; retreat from exchanges of social interaction, excessive fear or anxiety);
Immaturity (inappropriate crying, temper tantrums, poor coping skills); and
Learning difficulties (academically performing below grade level).

Children with the most serious emotional disturbances may exhibit distorted thinking, excessive anxiety, bizarre motor acts, and abnormal mood swings. Some are identified as children who have a severe psychosis or schizophrenia.

Many children who do not have emotional disturbances may display some of these same behaviors at various times during their development. However, when children have an emotional disturbance, these behaviors continue over long periods of time. Their behavior thus signals that they are not coping with their environment or peers.