This investigation defines the construct of dietary self-efficacy and examines the personal and interactional factors that predict efficacy in food behavior. Dietary self-efficacy is the belief that one is capable of behavior necessary to produce a nutritionally healthful diet. A path model was tested that located dietary self-efficacy as a consequence of the character of marital interaction (role disagreement, equity/inequity, and family food interaction), personal conditions of depression and low self-esteem, age, and education. One hundred fifty-five married couples were randomly selected and interviewed. The path model predicted a direct causal effect of role disagreement and inequity on depression and an indirect effect on dietary self-efficacy mediated by depression and self-esteem. The findings supported the proposed model for wives but not for husbands, suggesting that dietary self-efficacy is a female construct. Wives continue to take major responsibility for food selection and preparation, including the nutrition of children. Therefore, dietary self-efficacy gains a position of centrality for wives that is not independent of the effect of everyday interaction.