The authors describe social validity assessment of mindfulness education and practices among high school students (N = 84) participating in a 10-week instructional program. The participants rated their satisfaction with and acceptance of several program components, content areas, and outcomes, as well as their engagement in specific mindfulness practices. Nearly all of the participants rated the program favorably, reported many beneficial effects, and anticipated future use of mindfulness in their lives. They did not routinely perform voluntary formal guided meditations beyond the classroom but did engage in informal mindfulness practices preceding certain activities (e.g., preparing for a test, athletic competition, performance event) and going to sleep at night. The authors discuss these findings and the implications for designing school-based mindfulness education programs.