A Study of Escitalopram in the Treatment of Children and Adolescents With Generalized Anxiety Disorder

* Subject's parent/legal representative must give written informed consent, including privacy authorization, prior to study participation. The subject will complete an informed assent prior to study participation. * Subject meets DSM-5 criteria for a primary diagnosis of GAD at screening established by a comprehensive psychiatric evaluation and confirmed/supported using the Mini-International Neuropsychiatric Interview for children and adolescents (MINI Kid). * Male subjects who are sexually active with a partner of childbearing potential must use, with their partner, a condom plus an approved method of highly effective contraception from the time of informed consent until 14 days after the last dose of study drug. * Female subjects who are sexually active and are of childbearing potential must use, with their partner, an approved method of highly effective contraception from the time of informed consent until 14 days after the last dose of study drug. * Female subjects who are not of childbearing potential do not need to use any methods of contraception. This includes preadolescent and adolescent females who have not reached menarche. - Subject must have venous access enough to allow blood sampling and be compliant with blood draws as per the protocol.

* Current diagnosis of MDD, attention-deficit/hyperactivity disorder, or lifetime diagnosis of bipolar disorder, psychotic depression, schizophrenia or other psychotic disorder, feeding and/or eating disorder, obsessive-compulsive disorder, conduct disorder, oppositional defiant disorder, post-traumatic stress disorder, panic disorder, or pervasive development disorder. * Suspected or previously diagnosed intellectual disability disorder. * One or more first-degree relatives with diagnosed bipolar I disorder. * History of seizure disorder (other than febrile seizures). * History of electroconvulsive therapy at any time during the subject's lifetime. * Known hypersensitivity to escitalopram (escitalopram oxalate) or citalopram or any of the inactive ingredients or had frequent or severe allergic reactions to multiple medications. * Taking any medications that are contraindicated to escitalopram (escitalopram oxalate). * Inability to speak, read, or understand English well enough to complete the assessments. * No active suicidal ideation or lifetime history of suicidal behavior as assessed by Columbia-Suicide Severity Rating Scale (C-SSRS).