Research suggests that vitamin D, known mainly for its role in bone health, may have other roles in the body and that vitamin D deficiency may contribute to certain chronic diseases, such as cardiovascular disease. Recently, vitamin D has received growing attention due to the increased awareness of possible deficiencies among certain populations at risk of vitamin D deficiency. Most circulating 25-hydroxyvitamin D comes from exposure to UVB rays in natural sunlight. In 2010, the Institute of Medicine issued new recommendations that daily vitamin D intakes should be increased to 600 IU/day for children ages 1-18. However, even with these recommendations in place, roughly 20% of all children are below the recommended 20 ng/mL. Moreover, more than two-thirds of all children have levels below 30 ng/mL, including 80% of Hispanic children and 92% of non-Hispanic black children. Therefore, it is imperative to gain an understanding of: 1) what supplemental doses may be necessary for schoolchildren who are already at a disadvantage in achieving optimal levels of 25(OH)D due to factors such as living at a northern latitude, having high obesity rates, and where a large proportion of the population are Latino or African American; and 2) whether serum concentrations of 25(OH)D over 30 ng/mL in children prevent health risks.