Objective: To examine the relationship of cancer prevention-related nutrition knowledge, beliefs, and attitudes to cancer prevention dietary behavior. Subjects/setting: Noninstitutionalized US adults aged 18 years and older. Methods: Data collected in the 1992 National Health Interview Survey Cancer Epidemiology Supplement were analyzed. The supplement included questions to ascertain knowledge, beliefs, and attitudes and a food frequency questionnaire to ascertain nutrient intake. Statistics: Multivariate linear regression modeling was conducted to assess the hypothesized relationships. Results: After adjustment for relevant covariates (age, sex, education, total energy, perceived barriers to eating a more healthful diet), knowledge and belief constructs were predictive of dietary behavior. Specifically, fat, fiber, and fruit and vegetable intakes more closely approximated dietary recommendations for persons with more cancer-prevention knowledge. The strength of the associations between these constructs and dietary behavior varied in some cases according to level of education and perceived barriers to eating a healthful diet. Of the perceived barriers to eating a healthful diet, perceived ease of eating a healthful diet was most strongly and consistently predictive of intake. Conclusions: Research findings challenge dietetics practitioners to design diet- and health-promotion programs and activities that not only educate the public about the importance of diet to health, but also address barriers to dietary change.