Mental health conditions in childhood and adolescence are increasing in the U.S. population and require early intervention, as highlighted by a recent Surgeon General's Advisory on Protecting Youth Mental Health. These health issues, which have been exacerbated by the COVID-19 pandemic, impair functioning, and may lead to longer term reductions in quality of life. Young adolescents are likely to experience stressors including academic pressure, feelings of loneliness and isolation, and excessive exposure to social media, all of which have been made worse by the pandemic and associated disruptions. Universal preventive programs at school serve as an important strategy for equipping youth with coping skills to address current and future social and emotional challenges. Yoga and mindfulness programs have emerged as a promising preventive approach for schools and have proven feasible and acceptable. The current study evaluated a universal, school-based mindfulness and yoga program among youth aged 11-14 in a racially diverse, urban setting in the United States. Outcomes of interest included symptoms of anxiety and depression. Anxiety and depression symptoms decreased in the intervention group, although these differences were not statistically significant. In the control group, anxiety symptoms decreased but depression symptoms increased. The resulting time effect indicated a significant decrease in anxiety symptoms, while the time by group effect revealed a strong trend in depression symptoms. Future research should investigate the utility of yoga and mindfulness interventions for early adolescents in a larger population, and the differences in intervention effect among subgroups, with attention to longer term outcomes.