This pilot study investigated the effectiveness of Healthy Minds, Healthy Schools (HMHS), a universal school cognitive-behavioral therapy program aimed at improving anxiety and emotion regulation. Using a quasi-experimental design with open assignment to groups, elementary students were assigned to either the intervention (n = 186) or comparison (n = 94) group. Posttest scores for both groups were compared using the Mann-Whitney U-test. Statistically significant anxiety improvements at posttest were reported by participants in the intervention group only. No significant differences were found for self-reports of emotion regulation nor parental report of child anxiety or emotion regulation. Results provide some preliminary evidence for the use and potential benefits of implementing CBT-based techniques in schools to assist students in managing anxiety-related symptoms. This study also explored program implementation fidelity and adaptation. The completion rate of fidelity tracking forms was 94%. Of the completed forms (N = 113), 74% of lessons were delivered as described. Examining implementation factors and allowing for flexible program delivery may present as key considerations to the successful transfer and sustainability of clinically based interventions to the school context.