The Food Choice Questionnaire (FCQ), which measures the reported importance to a given individual of nine factors underlying food choice, and a food frequency questionnaire, were administered to 241 participants, who were also required to classify their diet as either 'standard', 'low in red meat' or 'vegetarian'. Respondents describing their diet as low in red meat attributed greater importance to health, natural content, weight control and ethical concern in their food choice than did those who described their diets as standard, whereas vegetarians differed significantly from those with a standard diet only on the score for ethical concern. Differences between men and women and between students and non-students in the frequency of consumption of a number of foods were shown to be mediated by differences in the importance attached to FCQ factors. Thus the generally healthier diets of women compared to men appeared to be accounted for by the greater importance attributed by women to weight control, natural content and ethical concerns.