This article describes the information currently available in the National Nutrition Monitoring System that is relevant to assessing the vitamin D status of US population groups, the strengths and limitations of this information, and selected results of vitamin D nutritional status assessments. The National Health and Nutrition Examination Survey (NHANES) provides information on vitamin D intakes only from 1988 to 1994. NHANES collected information on supplement use and circulating 25-hydroxyvitamin D [25(OH)D] concentrations from 1988 through current surveys. The National Nutrient Database for Standard Reference started providing limited data on the vitamin D content of foods in 2002 and continues to update these values. The Food Label and Package Survey provides 2006-2007 label information on vitamin D fortification of marketed foods. Despite limitations in the available data and controversies about appropriate criteria for evaluating vitamin D status among population groups, we can make some useful comparisons of vitamin D status among life-stage groups. In general, males have higher vitamin D intakes and 25(OH)D concentrations than do females. Children tend to have higher vitamin D status than adults. The increasing use of multivitamin-mineral dietary supplements in younger to older adults is not associated with a corresponding increase in serum 25(OH)D concentrations. In general, leaner individuals have higher circulating concentrations of 25(OH)D and supplement use than do heavier individuals. Finally, non-Hispanic whites tend to have higher vitamin D status than do non-Hispanic blacks and Mexican Americans.