Mental-health disorders are widely prevalent in children and adolescents, and social workers are the primary service providers for children and families experiencing these disorders. This entry provides an overview of some of the most commonly seen disorders in children and adolescents: attention deficit hyperactivity disorder, oppositional defiant disorder, conduct disorder, separation anxiety disorder, and specific learning disorders. The prevalence, course, diagnostic criteria, assessment guidelines, and treatment interventions are reviewed for each disorder. In addition, the key role of social workers in the identification and intervention of these disorders, as well as ways social workers can support the children and families experiencing these disorders, is discussed.