Treatment of mood disorders and suicidal behavior is complex. It requires knowledge of the proper diagnostic assessment of the disorders and familiarity with the changing concepts and evolving treatment strategies for these conditions. Accurate diagnosis is the key to successful treatment and requires a comprehensive psychiatric diagnostic evaluation, which includes interviews with the child, parents, and collateral informants (e.g., teachers, social services personnel). The psychiatric assessment of depressed and manic children and adolescents is difficult and must be performed by a clinician who pays attention to developmental, environmental, and cultural factors that may affect the patient's clinical presentation.