The Queensland Early Intervention and Prevention of Anxiety Project evaluated the effectiveness of a cognitive-behavioral and family-based group intervention for preventing the onset and development of anxiety problems in children. A total of 1,786 7- to 14-year-olds were screened for anxiety problems using teacher nominations and children's self-report. After recruitment and diagnostic interviews, 128 children were selected and assigned to a 10-week school-based child- and parent-focused psychosocial intervention or to a monitoring group. Both groups showed improvements immediately postintervention. At 6 months follow-up, the improvement maintained in the intervention group only, reducing the rate of existing anxiety disorder and preventing the onset of new anxiety disorders. Overall, the results showed that anxiety problems and disorders identified using child and teacher reports can be successfully targeted through an early intervention school-based program.