The Queensland Early Intervention and Prevention of Anxiety Project evaluated a child- and family-focused group intervention for preventing anxiety problems in children. This article reports on 12- and 24-month follow-up data to previously reported outcomes at posttreatment and at 6-month follow-up. A total of 1,786 7- to 14-year-olds were screened for anxiety problems using teacher nominations and children's self-report. After diagnostic interviews, 128 children were selected and assigned to either a 10-week school-based child- and parent-focused psychosocial intervention or a monitoring group. Both groups showed improvements immediately at postintervention and at 6-month follow-up; the improvement was maintained in the intervention group only reducing the rate of existing anxiety disorder and preventing the onset of new anxiety disorders. At 12 months, the groups converged, but the superiority of the intervention group was evident again at 2-year follow-up. Severity of pretreatment diagnoses, gender, and parental anxiety predicted poor initial response to intervention, whereas pretreatment severity was the only predictor of chronicity at 24 months. Overall, follow-up results show that a brief school-based intervention for children can produce durable reductions in anxiety problems.