Childhood mood disorders such as major depression, dysthymia, and bipolar disorder have been found to be highly prevalent among children and adolescents. The emotional and behavioral dysfunction associated with these mood disorders can cause impairments across areas of functioning, including academic and social arenas. This article reviews the course, possible causes, assessment, and treatment of this group of disorders in youth and concludes by examining the implications for nurses and other health care providers of youth with mood disorders.