This booklet is part of the National Institute of Mental Health's efforts to educate the public and health care professionals about panic disorder. Discussed here are the causes, definition, and symptoms of the disorder. Panic attacks, which can seriously interfere with a person's life, may strike more than three million U.S. citizens at some time in their lives. Individuals who suffer panic attacks may also develop phobias, especially agoraphobia, in which a person avoids places or situations where help may not be forthcoming if an attack occurs. Treatment, it is claimed, can bring significant relief to 70 to 90 percent of people with panic disorder. Several kinds of treatment approaches, by themselves or in combination, may be effective: (1) cognitive-behavioral therapy, where the person modifies or eliminates troublesome thought patterns and behaviors; (2) pharmacotherapy, in which prescription medication is used both to prevent panic attacks or reduce their frequency and severity; and (3) psychodynamic therapy, where the therapist and the patient work together to uncover emotional conflicts which may underlie the patient's problems. Other conditions may accompany a panic disorder and health care personnel should be careful to identify these. The reader will find strategies and tips on how to cope with a panic attack, as well as information on where individuals may seek further help. (RJM)