The mood stabilizers lithium and valproate have been used to treat children and adolescents with mood and seizure disorders for many years. Lithium was first used over 40 years ago to treat "manic-depressive" illness in children (Annell 1969). Since then, a variety of "mood stabilizing" agents have been used to treat psychiatric disorders in children and adolescents. The mood stabilizers can be divided into the traditional agents—lithium, valproate, and carbamazepine—and the newer or "novel" agents. The novel mood stabilizers include lamotrigine, oxcarbazepine, topiramate, and gabapentin (Weisler et al. 2006). These agents have migrated from pediatric neurology to child psychiatry after clinicians noticed their behavioral effects. All of these drugs have been used to treat children and adolescents with mood and/or behavior problems, and all of these agents, except lithium, are used to treat seizure disorders. Now that six atypical antipsychotics are available in the United States, these mood stabilizers are not prescribed as often as they once were. Lithium and valproate are still often used to treat bipolar disorder in children and adolescents, and the evidence base for the safety and efficacy of these two mood stabilizers as well as the newer antiepileptic agents in children and adolescents is steadily increasing (Kowatch and DelBello 2006; Pavuluri et al. 2005).