Increasing rates of childhood overweight have been linked to the rising energy density of the diet. We sought to provide temporal profiles of dietary energy density (DED) in a nationally representative sample of U.S. children and adolescents < or = 19 y old and to describe associations between DED and predictors of overweight. We used a subset of data from the 1994-1996, 1998 Continuing Survey of Food Intake for Individuals (CSFII) and a multivariate regression model to determine independent associations between DED and socioeconomic and demographic variables after controlling for covariates. In this cross-sectional data set, DED was positively associated with total energy intakes and varied with both age and gender. DED increased from birth, peaked at 7-8 y of age, and then declined. Boys consumed more energy-dense diets than girls. Among children < or = 4 y old, higher DED was associated in the regression model with lower household incomes and with enrollment in the food stamp program. Among adolescents 12-19 y old, higher DED was associated with being African-American. In contrast, lower DED among children < or = 11 y old was associated with being Asian or Hispanic and with total daily consumption of fluid milk. The quality of the diet for young children, as indexed by high DED, may be adversely affected by limited household economic resources. Although food insecurity and WIC enrollment were not associated with DED in this study sample, milk consumption in children < or = 4 y old was associated with lower DED.