INTRODUCTION: School-age children report much stress in their daily lives, which may lead to psychological and physical problems. Mindfulness-based Stress Reduction is a program of awareness-based practices effective with adults. The purpose of this study was to investigate the efficacy of mindfulness training through yoga with school-age girls to reduce perceived stress, enhance coping abilities, self-esteem, and self-regulation, and explore the relationship between the dose of the intervention and outcomes. METHOD: Fourth- and fifth-grade girls were recruited from two public schools and randomly assigned to intervention and wait-list control groups. The intervention group met 1 hour a week for 8 weeks and completed 10 minutes of daily homework. RESULTS: Self-esteem and self-regulation increased in both groups. The intervention group was more likely to report greater appraisal of stress (p < .01) and greater frequency of coping (p < .05). Homework accounted for 7% of the variance in reported stress. DISCUSSION: Consistent with reports of mindfulness training, greater awareness of the feelings associated with stress may enhance coping abilities. However, it is possible that the increasing awareness of stressors in itself increased stress, possibly as part of the process of developing mindfulness or related to cognitive, emotional, or social development. Mindfulness in children may differ from mindfulness in adults and warrants further investigation.