Schizophrenia is characterized by disturbances in perception, thought, emotion, affect, and social relatedness. Early-onset schizophrenia (EOS) is defined as onset prior to age 18 years, with childhood-onset schizophrenia (COS) referring to onset before age 13 years. EOS is considered to be continuous with adult-onset schizophrenia yet manifests with special developmental and social challenges. This chapter will provide information on history, etiology, neurobiological and genetic characteristics, clinical presentation, and an overview of psychosocial and pharmacological interventions to provide a basis for comprehensive care of children and adolescents with schizophrenia and related disorders.