 The present study was a randomized controlled trial that explored the feasibility, acceptability, and effectiveness of short-term mindfulness training among adolescents. The primary purpose was to investigate the effectiveness of two main Mindfulness-Based Stress Reduction componentssitting meditation and hatha yogaon working memory, stress, anxiety and mindfulness. The influence of daily home practice compliance on intervention outcomes was also examined. Participants N 198 adolescents were recruited from a large public middle school in southern California. Participants were randomly assigned to sitting meditation, hatha yoga, or a waitlist control group. Participants were asked to complete a computerized working memory task, and self-report measures of perceived stress, anxiety, and mindfulness at pre- and post-interventionwaitlist, as well as one-month follow-up. A series of mixed-design analyses of variance ANOVAs were used to examine changes in working memory, stress, anxiety, and mindfulness between groups at pre- and post- intervention. 