Mindfulness based interventions (MBIs) for teachers can improve classroom interactions, teacher mindfulness, and well-being, yet whether teacher focused MBIs also benefit children remains largely unexplored. This cluster randomized trial with 36 urban elementary schools, 224 K-5th grade teachers (M[subscript age] = 41.5) and 5200 children (M[subscript age] = 7.7 years, tested direct and moderated effects of the Cultivating Awareness and Resilience in Education (CARE) professional development program on eight child academic and social emotional outcomes, most teacher-reported. Positive effects of CARE were found for engagement in learning, motivation for learning, and reading competence. CARE was unexpectedly related to increased conflict. CARE teachers initially low in mindfulness reported children as higher on engagement, motivation, reading competence, and math competence compared to children of control group teachers low in mindfulness. Unexpectedly, CARE teachers high in mindfulness at baseline reported children as lower in social skills compared to high mindfulness teachers in the control condition. [This is the online first version of an article published in "Applied Developmental Science."]