The search for medicinal agents to improve emotional, behavioral, and psychiatric conditions of Homo sapiens has occurred for ages. The 20th century witnessed the development of psychopharmacologic agents, including stimulants in the 1930s (and 1950s), chlorpromazine in the 1950s, lithium, tricyclic antidepressants, benzodiazepines, SSRIs (1990s), and others. The proper use of these agents in the pediatric population continues to be an active study. Atypical antipsychotics have been approved by the FDA for children and adolescents though their safety and efficacy in the pediatric population but must be assiduously ascertained with ongoing research in the eternal iatric maxim of primum non nocere. The science of evidence-based pharmacotherapy for mental health disorders in children and adolescents is finally emerging. Exciting discoveries await the researchers of this still early 21st century lead by the crucial collaborative efforts of academicians, pharmaceutical scientists, and medical government authorities. Controversies regarding the use of various psychopharmacologic agents for the pediatric population continue in the 21st century, requiring further research and insightful judgment for its applications in this vulnerable population. Excessive and unnecessary psychopharmacologic agents should be avoided in the pediatric population with behavioral/emotional/psychiatric conditions/disorders. In this second edition, the authors present updated information about psychopharmacology in childhood and adolescence.