Anxiety disorders are the most common mental health problems in youth, affecting 8–27 % of youth (Costello, Egger, & Angold, 2005). These disorders represent serious mental health problems for children and adolescents and lead to daily distress and impairment, peer and social relation problems (Chansky & Kendall, 1997; Langley, Bergman, McCracken, & Piacentini, 2004; Piacentini, Peris, Bergman, Chang, & Jaffer, 2007; Strauss, Forehand, Smith, & Frame, 1986), and significant difficulties in academic achievement (Kessler, Foster, Saunders, & Stand, 1995; King & Ollendick, 1989). Additionally, anxious youth often have poor self-esteem, more physical problems, and greater family conflict and distress than their peers (Ezpeleta, Keeler, Alaatin, Costello, & Angold, 2001; Harter, Conway, & Merikangas, 2003; Strauss, Frame, & Forehand, 1987). If untreated, childhood anxiety disorders tend to be chronic and unremitting in their course (Aschenbrand, Kendall, Webb, Safford, & Flannery-Schroeder, 2003; Keller, et al., 1992; Pine, Cohen, Gurley, Brooks, & Ma, 1998) and predict the development of other psychopathology later in life (Last, Perrin, Herson, & Kazdin, 1996; Woodward & Fergusson, 2001) including depression (Brady & Kendall, 1992; Cole et al., 1998; Pine et al., 1998; Seligman & Ollendick, 1998), externalizing disorders, and substance use disorders (Bittner et al., 2007, Costello et al., 2003, Last et al., 1996).