Technical Abstract: Many adults take vitamin mineral supplements, but there is relatively little up-to-date information available on vitamin-mineral supplement use among adolescents. In the 1998 Child and Adolescent Trial for Cardiovascular Health Tracking Study (CATCH III), a school-based dietary intervention sponsored by the National Heart, Lung and Blood Institute at four sites around the country, 1,532 eighth-grade students were surveyed and provided reports on their dietary intakes of supplements. Eighteen percent of the eighth graders surveyed reported using vitamin-mineral supplements on the 24-hour recall. Of those users, 47% took multivitamin and/or multi-mineral preparations, 37% used single nutrient supplements (mostly vitamin C), 16% used other combinations, 8% used supplements other than vitamins or minerals, and 4% did not provide enough detail to ascertain what was taken. Adult doses were reported more commonly than child doses. Users reported a mean of 1.4 supplements each of the eighth graders who took vitamin-mineral supplements, the majority took only one supplement (77%), 15% took 2 supplements, and only 8.2% (or about 1.5% of all students queried) took 3 or more supplements. Intakes rarely exceeded upper tolerable levels. Users had higher intakes for 16 of the 20 micronutrients studied, and these differences remained after adjusting for gender, race/ethnicity, site, treatment condition, and within-school variability. Eighth-grade students use vitamin and mineral supplements to a much greater extent than previously. More studies are needed to better characterize supplement users in childhood and its impact on child nutrition.