OBJECTIVE: This preliminary study tests the effectiveness of an elementary school-based stress management technique on anxiety symptoms and heart rate variability (HRV) in children. METHODS: In this controlled prospective longitudinal study, children in third-grade classroom participated in a teacher-led daily 10-minute stress management intervention for 4 months. The control class teacher read from a children\'s book for 10 minutes daily. A standardized anxiety scale and HRV (using computer biofeedback program) were measured before the 4-month intervention, immediately after, and 1 year later. RESULTS: The intervention class showed significant improvement from baseline to the immediate postintervention period in total anxiety (N = 14, F = 12.95, p = .002), with 1-year follow-up scores maintaining improvement (N = 13, F = 5.88, p = .025). The intervention class had small improvement in HRV using the biofeedback program in the immediate postintervention period, with significant improvement at 1-year follow-up (N = 13, F = 10.61, p = .005). The control class showed no improvements. Qualitatively, children reported that the intervention was helpful during stressful times at school and at home, even after the study period. CONCLUSION: An elementary school-based short daily stress management intervention can decrease symptoms of anxiety, and improve HRV, a measure of relaxation. Ultimately, these children found this skill continued to help them cope better with everyday stressors.