This study examined anxiety development in median- (n = 74) and high-anxious children (n = 183) aged 8–13, the effect of parent- and child-focused preventive interventions on child/parental anxiety, and the effect of parental anxiety on child anxiety. High-anxious children were randomized into a parent-focused (n = 69), child-focused (n = 58) or non-intervention (n = 56) group. Families completed a pretest and 1- and 2-year follow-ups. Children selected as high-anxious or at risk were found to remain more susceptible to having anxiety problems and developing anxiety disorders than median-anxious children. Both intervention types showed favorable outcomes compared to no intervention on the number of “ADIS improved” children. These findings underline the need for effective preventive interventions for child anxiety. General improvements over time were found for symptoms of child and parental anxiety, however, and parental anxiety did not predict improvement in child anxiety after controlling for intervention. Therefore, it may not be necessary to focus on parental anxiety in interventions aimed at preventing child anxiety.