A study examined children's conceptions about nutrients and the dimensions underlying their classifications of foods into groups. Children (5 to 11 years old) classified 71 foods into groups by whatever criteria they wished. These classifications were recorded, as were the children's answers to questions about nutrients and their responses in tasks assessing cognitive developmental level. Analysis of classification data yielded four major food groups. One difference from the "Basic Four" food groups involved the presence of a sweets group. Analysis revealed common underlying dimensions of sweet vs. non-sweet foods and meal entrees vs. drinks and breakfast foods, suggesting that perceptual, functional, and physical properties of foods influenced food classifications. Only"concrete operational" children were influenced by dimensions involving degree of food processing and food origin. Understanding of nutrients improved with cognitive developmental level, but generally poor understanding was evident. Results highlight the need to design health education curricula that are appropriate to students' cognitive developmental levels. (Authors/CJ)