This study examined the impact of neighborhood material deprivation on gender differences in body mass index (BMI) for urban Canadians. Data from a national health survey of adults (Canadian Community Health Survey Cycles 1.1/2.1) were combined with census tract-level neighborhood data from the 2001 census. Using multilevel analysis we found that living in neighborhoods with higher material deprivation was associated with higher BMI. Compared to women living in the most affluent neighborhoods, women living in the most deprived neighborhoods had a BMI score 1.8 points higher. For women 1.65 m in height (5'4'' inches), this translated into a 4.8 kg or 11 lb difference. For men, living in affluent neighborhoods was associated with higher BMI (7 lb) relative to men living in deprived neighborhoods. The relative disadvantage for men living in pockets of affluence and women living in pockets of poverty persisted after adjusting for age, married and visible minority status, educational level, self-perceived stress, sense of belonging, and lifestyle factors, including smoking, exercise, diet, and chronic health conditions. The implication of these disparate findings for men and women is that interventions that lead to healthy weight control may need to be gender responsive. Our findings also suggest that what we traditionally have thought to be triggering factors for weight gain and maintenance of unhealthy BMI-lifestyle and behavioral factors-are not sufficient explanations. Indeed, these factors account for only a portion of the explanation of why neighborhood stress is associated with BMI. Cultural attitudes about the body that pressure women to meet the thin ideal which can lead to an unhealthy cycle of dieting and, subsequent weight gain, and the general acceptability of the heavier male need to be challenged. Education and intervention within a public health framework remain important targets for producing healthy weight.