There is clear evidence that mindfulness is a beneficial trait and one that can be cultivated with training. However, science has made relatively modest progress in developing our ability to measure mindfulness. To date, most research relies heavily on asking people how mindful they are, gathering assessments that may or may not accurately reflect reality. This project is focused on exploring alternative methods for measuring mindfulness. In particular, we are asking mindfulness instructors to rate the level of trait mindfulness in participants in Mindfulness-Based Stress Reduction classes. We will examine the degree to which these expert ratings reflect individuals’ self-report as well as their performance on a computerized task designed to measure mindfulness (the breath counting task). In a separate study, we are having both naïve raters (undergraduate students) and meditation teachers rate a sample of still images on dimensions theoretically related to mindfulness. These images were taken before or after a larger randomized controlled trial that compared a mindfulness-based intervention to either another treatment or a waitlist. These data will help determine whether observable changes occur over the course of mindfulness training and the degree to which raters’ assessment relate to other measures of mindfulness and related constructs.