Researchers repeatedly find that immigrants are healthier than their native‐born counterparts. Among immigrant children, however, findings are mixed. Moreover, the effect of neighborhood context on obesity has not been fully examined. Using the National Longitudinal Study of Adult Health, this study investigates the linkages between acculturation, neighborhood characteristics, and obesity among young adults, including the potential for residing in an immigrant neighborhood, to mediate the adverse effects of low neighborhood socioeconomic conditions on obesity. Consistent with the unhealthy assimilation model, an immigrant health advantage is found for first generation Asians. Conversely, a greater likelihood of being obese is found for second and third and higher generation Hispanics relative to third and higher generation Whites. Further, a high concentration of immigrants and linguistically isolated households appear to work as a buffer against health risks that relate to obesity, particularly in poor neighborhoods.