The purpose of this study was to examine 3 possible explanations for the documented association between cereal consumption and positive health outcomes. The study design was a descriptive, longitudinal study known as the National Heart, Lung, and Blood Institute Growth Health Study. Data from annual 3-day food records were analyzed to answer study questions. The National Heart, Lung, and Blood Institute Growth Health Study recruited 2379 girls (1166 white and 1213 black), age 9 to 10 at baseline. Frequency of consumption of breakfast cereal; other types of foods eaten at breakfast; and macronutrients, micronutrients, beverages, and fruits and vegetables and physical activity were the main outcome measures. The association of type of breakfast (cereal breakfast vs breakfast without cereal) with the outcomes of interest was estimated using regression techniques. The major findings were (1) cereal consumed at breakfast provided more fiber, iron, folic acid, and zinc and less fat, sodium, sugar, and cholesterol, compared with the nutrients in foods eaten during noncereal breakfasts. The cereal consumed provided less protein, carbohydrates, and calcium, compared to foods consumed during noncereal breakfasts; (2) eating cereal for breakfast appeared to facilitate milk consumption (leading to increased calcium intake) and to displace fats/sweets, quick breads, soda, and meat/eggs as breakfast foods. Eating cereal at breakfast was associated with increased consumption of fiber and carbohydrates and decreased consumption of fats throughout the day; and (3) greater physical activity was also associated with cereal breakfast. In conclusion, cereal consumption as part of a healthy lifestyle may play a role in maintaining adequate nutrient intake and physical activity among girls.