Emotional disturbances in children and youth occur at alarmingly high rates, are associated with a number of negative life consequences, and come at a tremendous cost to society. A Year Book of Australia report indicated that 20% of children between the ages of 12 and 16 had a significant mental health problem (Stanley, 2002). Anxiety disorders are the most frequently experienced mental health disorder in childhood and adolescence, with studies stimating a point prevalence of 5% to 10% and a lifetime prevalence of approximately 20% (Essau, Condradt, & Petermann, 2000; Shaffer, Fischer, Dulcan, & Davies, 1996). Research has demonstrated that anxiety and depressive
symptoms are highly related in child and youth populations (e.g., Dobson, 1985; Tannenbaum, Forehand, & Thomas, 1992). Estimates indicate approximately 2% to 5% of children and adolescents will suffer a major depressive disorder of clinical severity (Kashani et al., 1987; Lewinsohn, Clarke, & Rohde, 1994). Beyond the high prevalence rates, these emotional disorders are associated with a wide range of psychosocial impairments, tend to be chronic and unremitting in course, and are associated with significant risk for other psychological disorders if left untreated (e.g., Cole, Peeke, Martin, Truglio, & Seroczynski, 1998; Kashani & Orvaschel, 1990; Last, Hansen, & Franco, 1997; Orvaschel, Lewinsohn, & Seeley, 1995).
There has been a recent surge in the field of prevention research for children and youth. Given the potential of such approaches to impact on the incidence and prevalence of childhood emotional disorders, the need for evidence-based prevention is strong. Primary preventive interventions can be defined as either universal, selected, or indicated and targeted (Mrazek & Haggerty, 1994). Universal interventions target whole population groups, selective interventions involve children and youth identified as at risk of psychological problems, and indicated interventions target individuals identified with mild to moderate symptoms of a disorder (Mrazek & Haggerty, 1994). Universal prevention interventions conducted in the school context have many advantages, including reducing recruitment, screening, and attrition difficulties; reaching a broad range of children and adolescents with varying levels of risk for psychopathology; reducing stigmatization; enhancing peer support; and reducing psychosocial difficulties within the classroom—thus promoting  learning and healthy development (Evans, 1999; Kubiszyn, 1999). Support for preventative outcomes based on the delivery of cognitive behavioral interventions in schools is growing.
The Queensland Early Intervention and Prevention of Anxiety Project (Dadds, Spence, Holland, Barrett & Laurens, 1997) represented the first cognitive behavioral trial for prevention of childhood anxiety. This study targeted children (ages 7 to 14 years) who were disorder-free but exhibited anxious symptomatology (indicated prevention; Mrazek & Haggerty, 1994) as well as children who met criteria for an anxiety disorder but were in the less severe range (early intervention; Mrazek & Haggerty, 1994). Screening identified 128 eligible participants who were randomly allocated to either an intervention or a control condition. Diagnostic status was used as an outcome measure, and results were favorable. Both groups demonstrated improvement immediately postintervention; however, by 6-month follow-up, the improvement was maintained in the intervention group only. No differences between groups were evident at 12-month follow-up; however, at the 2-year follow-up, intervention effectiveness was demonstrated through the reduction of existing rates of anxiety disorder and prevention of the onset of new
anxiety disorders (Dadds, Spence, Laurens, Mullins,& Barrett, 1999). Consistent with prior research (Last, Perrin, Hersen, & Kazdin, 1996), regardless of intervention status, participants in this study showed a general improvement across time; results further revealed gender (female), parental anxiety and pretreatment severity predicted poor response to intervention (Barrett, Dadds, & Rapee, 1996; Cobham, Dadds, & Spence, 1998). This study  emonstrated that anxiety disorders and the number of children at risk of anxiety can be successfully reduced through selected school-based cognitive–behavioral intervention. An interesting outcome was putative delay in intervention effects, which is consistent with the results of a similar prevention trial for adolescent depression (Jaycox, Reivich, Gillham, & Seligman, 1994).