Mindfulness-based interventions (MBIs) are programs designed to improve psychological well-being, based on the practice of mindful awareness. One such MBI is the MindUP program, which is a school-based program designed for middle school students implemented by classroom teachers. MindUP has been shown to enhance indices of psychological well-being. Our team is interested in understanding how MindUP works, biologically. Recently, we have shown that MindUP influences stress biology in children, namely the activity of the stress hormone cortisol. As a follow-up study, we aim to investigate whether or not MindUP also impacts epigenetic processes. Epigenetics refers to environmental modifications to the activity of genes. We aim to recruit 100 grade 6 students and their teachers to participate in a randomized control trial of MindUP. All participants will be assessed on a variety of psychological measures at baseline and follow-up. Saliva will also be collected at both time-points for epigenetic analyses. We hypothesize that the MindUP program will alter the activity of genes in saliva which are important for stress biology, and that these changes will coincide with expected improvements in psychological well-being. This work will hopefully better elucidate the biology of mindfulness, and may contribute to the design of more effective MBIs.