Suicidal behavior is a matter of great concern for clinicians who deal with the mental health problems of children and adolescents. The incidence of suicide attempts reaches a peak during the mid-adolescent years; and mortality from suicide, which increases steadily through the teen years, is the third leading cause of death at that age. Mood disorders (particularly early-onset major depressive disorder), anxiety disorders, substance abuse, and runaway behavior independently increase the risk of suicide attempts in both sexes. Suicide attempts are more common in girls than boys. Assessment of suicidal patients requires an evaluation of the suicidal behavior and determination of risk for death or repetition, as well as an assessment of the underlying diagnoses or promoting factors. This article discusses the identification of risk. A discussion of treatment for suicidal behavior addresses acute management, psychotherapies, and psychopharmacology. A review of epidemiology focuses on age, gender, secular changes, geography, and suicide methods. Also discussed are clinical characteristics of teenagers who commit suicide, risk factors for suicide, the epidemiology of nonlethal suicidal behavior, the clinical presentation of suicidal behavior, inpatient care and partial hospitalization, outpatient treatment, specific psychotherapies, prevention methods, postvention, conflict of interest, and scientific data and clinical consensus. 189 references and appended selected Web sites with suicide facts and resources