Anxiety is a biological warning mechanism with intense feelings of fear that prepares us for action. It should be differentiated from the normal fear response. Anxiety disorders are one of the most common psychiatric disorders in children and adolescents, but they often go undetected or untreated. Childhood anxiety may be underestimated due to various factors. The prevalence of anxiety in a community depends on many factors, including race, sex, type of the anxiety, and the adequacy of the epidemiological studies. The development of anxiety disorders in children and adolescents involves interplay between heritable factors, developmental factors, cognitive and learning factors, neurobiological factors including genetic, social and environmental factors. Anxiety disorders in children and adolescents are often associated with other psychiatric disorders including other anxiety disorders, depression, attention-deficit hyperactivity disorder (ADHD), oppositional defiant disorder, substance abuse, and other psychiatric disorders. Management of anxiety disorders in children needs and integrative team- work including cognitive behavioral therapy, mindfulness- based psychotherapies, psychodynamic psychotherapies, and psychopharmacologic treatments.