This study examines the causal relationship between dietary knowledge and behavior by including self-efficacy in the models. Regression analyses supported the hypothesized relationships that self-efficacy mediates effects of dietary knowledge and social influences on dietary behavior. Self-efficacy also accounted for variance in eating behavior not explained by knowledge or demographic variables. The coefficients for the relationship between dietary behavior and knowledge decreased for each of the four dietary models when the influence of self efficacy was added. Interventions and health promotion campaigns should seek to directly address factors influencing diet related self-efficacy instead of focusing on disseminating information only.