Context: Commercial marketing is a critical but understudied element of the sociocultural environment influencing Americans' food and beverage preferences and purchases. This marketing also likely influences the utilization of goods and services related to physical activity and sedentary behavior. A growing literature documents the targeting of racial/ethnic and income groups in commercial advertisements in magazines, on billboards, and on television that may contribute to sociodemographic disparities in obesity and chronic disease risk and protective behaviors. This article examines whether African Americans, Latinos, and people living in low‐income neighborhoods are disproportionately exposed to advertisements for high‐calorie, low nutrient–dense foods and beverages and for sedentary entertainment and transportation and are relatively underexposed to advertising for nutritious foods and beverages and goods and services promoting physical activities.

Methods: Outdoor advertising density and content were compared in zip code areas selected to offer contrasts by area income and ethnicity in four cities: Los Angeles, Austin, New York City, and Philadelphia.

Findings: Large variations were observed in the amount, type, and value of advertising in the selected zip code areas. Living in an upper‐income neighborhood, regardless of its residents' predominant ethnicity, is generally protective against exposure to most types of obesity‐promoting outdoor advertising (food, fast food, sugary beverages, sedentary entertainment, and transportation). The density of advertising varied by zip code area race/ethnicity, with African American zip code areas having the highest advertising densities, Latino zip code areas having slightly lower densities, and white zip code areas having the lowest densities.

Conclusions: The potential health and economic implications of differential exposure to obesity‐related advertising are substantial. Although substantive legal questions remain about the government's ability to regulate advertising, the success of limiting tobacco advertising offers lessons for reducing the marketing contribution to the obesigenicity of urban environments.