Six hundred and four grocery shoppers were observed unobtrusively at three supermarkets to investigate the relationship between grocery purchasing and the factors of obesity, assumed food deprivation, social class, and meal hour. It has been suggested that shoppers will purchase more if they shop prior to eating rather than after (Stuart & Davis, 1972), although such a notion conflicts with Schachter's (1971) internal-external hypothesis and with the conclusions of one field study (Nisbett & Kanouse, 1969). We found that female shoppers who shopped prior to standard meal times consistently purchased more than those who shopped after meal times (P less than 0.001), regardless of social class or meal hour. Males displayed the same tendency though differences were not significant. No obese-normal differences were found for either sex. A negative relationship between obesity and social class was found amoung females (P less than 0.001).