Existing studies suggest that mindfulness-based interventions (MBIs) can reduce ADHD symptoms when delivered as targeted clinical programs to young people diagnosed with ADHD. However, there is currently a lack of research on whether MBIs are effective in reducing elevated ADHD symptoms when delivered as universal programs to whole classes in schools. This study investigated the effects of a universal nine-week MBI (.b program) on students’ elevated ADHD symptoms using an cluster randomized…