An epidemiologic study was carried out on Mexican Americans and Anglos residing in two socioeconomically and culturally distinct target areas in San Antonio: a middle income, ethnically integrated area ("transitional") and an upper income, predominantly Anglo area ("suburbs"). Although suburbanite Mexican Americans were leaner than their lower income counterparts, they were still more overweight than suburbanite Anglos. Even after adjusting for these differences in relative weight, however, Mexican Americans were still more likely than Anglos to express the opinion that Americans are too concerned about losing weight. Expressed as a per cent of the maximum score, Mexican American women in the transitional neighborhood scored 77% on this attitude item compared with 60% for Angle women (p less than 0.0005). Comparable ethnic differences on this attitude item were found in men in the transitional neighborhood and in suburbanites of both sexes. In the transitional neighborhood Mexican American women scored lower than Anglo women on a "sugar avoidance" and a "dieting behavior" scale: 23% for Mexican Americans and 45% for Anglos (p less than 0.0005) on the "sugar avoidance" scale. Comparable ethnic differences on this scale were found for men in the transitional neighborhood and for both sexes on the "dieting behavior" scale. Although no ethnic differences on these behavioral scales were found in the more affluent suburbs, these results nevertheless have public health relevance because the majority of Mexican Americans in the United States are of low socioeconomic status.