Data for 5,884 adults (19 years of age and older) who participated in the 1987-88 Nationwide Food Consumption Survey (1987-88 NFCS) were used to investigate demographic and economic factors associated with dietary quality. Although the low response rate for the 1987-88 NFCS has raised concerns about possible bias, it is appropriate to use this extensive data set for analyses that do not attempt to generalize the results to the US population as a whole. Two aspects of quality were calculated for the mean of the 3-day reported intakes: number of nutrients below two thirds of the 1989 Recommended Dietary Allowance (RDA) (low-intake nutrients) and percent of energy from fat. Few adults reported mean intakes that met suggested guidelines: 22% of diets were above two thirds of the RDA for all 15 nutrients and 14% were below 30% fat, but only 2% met both criteria. Energy intake was a strong negative predictor of number of low-intake nutrients and a weak positive predictor of percent of energy from fat. Results of multivariate regression analyses identified few demographic or economic predictors of either the number of low-intake nutrients or percent of energy from fat. According to these data, diets of most adults do not conform to current dietary guidelines. Nutrition education efforts should be directed to all adults, and research should be undertaken to determine more effective ways to help adults improve their overall dietary quality.