Anxiety disorders are the most common psychiatric illnesses in children and adolescents. They are associated with significant distress and impairment. Most of the children and adolescents with anxiety disorders are not detected and only a minority receives adequate treatment. Anxious children and adolescents often follow a chronic course of disease with elevated risk of depressive disorders, substance abuse and even suicide. Risk factors for anxiety disorders are complex and consist of intricate interplay of multiple factors, including genetic makeup and environmental risks. Effective, evidence-based treatments for anxiety disorders in children and adolescents consist of cognitive-behavioral therapy and pharmacotherapy with serotonin specific reuptake inhibitors. Further research is needed to design high-quality screening tools for anxiety disorders in the primary care setting.