Anxiety disorders and depression are among the most common psychiatric illnesses affecting youth. Anxiety disorders typically begin in childhood, whereas the onset of depression frequently occurs later during adolescence or early adulthood. These illnesses are highly comorbid, with pathological anxiety regularly preceding the development of depression. The lifetime prevalence of anxiety disorders when assessed in adolescents is reported to be as high as 32% (1), whereas the estimated 12-month prevalence of major depression in adolescents is approximately 13% (2). Prior to adolescence, the incidence of these disorders is the same between boys and girls; however, as girls mature and go through puberty, they are approximately twice as likely as boys to be diagnosed with anxiety and major depression. In addition to causing considerable suffering and impaired functioning, when severe, these illnesses can be life threatening. Tragically, 6,200 suicide deaths were reported in 2017 among U.S. adolescents and young adults from 15 to 24 years of age (3), and suicide is the second leading cause of death among individuals 10–34 years of age (4).