Few studies have taken a conventional quantitative environmental justice approach to assessing the inequitable implications of climate change at a fine scale, such as across neighborhoods within an urban area. In this paper, we test the "environmental justice hypothesis" for climate change-related variables in the bi-national context of El Paso, Texas and Ciudad Juarez, Chihuahua using a matched set of social indicators from the 2000 US and Mexican censuses and biophysical data related to heat, ozone and flooding. T-test results demonstrated that social marginality and climate change-related hazard exposure were generally higher in Juarez as compared to El Paso. Using spatial regression models, we found patterns of environmental injustice in the sister cities related to these climate change-related hazards. Lower social class neighborhoods generally faced increased risks from extreme heat in both cities, and from floods and peak ozone in El Paso. In El Paso, children also faced significant and disproportionate exposure to peak ozone, while female-headed households were significantly more burdened by flooding and peak ozone in Juarez. Despite the limitations of this cross-sectional study, we can expect injustices to heighten as neighborhoods at-risk now become increasingly exposed under climate change scenarios. In sum, this analysis provides a model for investigating inequities associated with future small area impacts of climate change. (C) 2011 Elsevier Ltd. All rights reserved.