In Australia, 14% of children and adolescents have a significant mental health problem, which is similar to global prevalence estimates of 12%. Teaching children techniques in mindfulness meditation has been recommended to improve their mental health. However, the recommendations are based mainly on efficacy in adult clinical trials, and insufficiently on trials with children and adolescents in a classroom setting. This mindfulness meditation pilot project involved training teachers at two primary schools in the outer suburbs of Melbourne, Australia to deliver a ten-week mindfulness curriculum and optional daily mindfulness exercises to students in grades 5 and 6 (ages 10 to 12). Pre- and post-program, students completed the Strengths and Difficulties Questionnaire (SDQ) and a modified version of the Children's Depression Inventory (CDI). On both scales there was a significant decrease in overall average score and the number of children in the diagnostic categories, 25.6% scoring in the borderline or diagnostic category for the SDQ pre-program and 16.3% post-program. For the CDI this was 25.8% pre- and 21.6% post-. The study is limited by its use of a pre-post design without comparison group. However, qualitative findings from teachers assist in discerning key themes, and this pilot study suggests the potential of more formal experimental testing of mindfulness training as an element of a whole-school mental health promotion program.