Over the past three decades, the environmental justice movement has developed out of growing concern about unequal distribution of environmental harm and unequal access to environmental resources. The mainstream environmental movement has been criticized for failing to address adequately environmental justice issues. Several scholars have claimed that environmental education has also failed to incorporate environmental justice concepts regarding the unequal distribution of environmental harm, but no studies thus far have tried to measure this claim empirically. This content analysis examines the level of inclusion of environmental justice concepts, as well as their context of representation, within mainstream, US national, 6-12 environmental education curricula. National curricula from Project WILD, Project Learning Tree, Project WET and the World Wildlife Fund were examined in this study. All guides were developed between the late 1990s and early 2000s, but were revised more recently. A total of 224 lessons were reviewed and evaluated based on several environmental justice indicators, with consideration for the presence of these indicators and whether they were presented within an environmental justice context. The lessons were also coded for implied environmental justice content and supplementary sections of the educational guides, such as appendices and conceptual frameworks, were also coded. The results suggest that these curriculum guides often address issues related to environmental justice (e.g. environmental health impacts on humans); however, they rarely present the issues within an explicit environmental justice context. The guides also rarely address issues traditionally considered to be environmental justice issues. The results show many missed opportunities to incorporate environmental justice, indicating that lessons could be adapted easily to be more inclusive. These results reveal potential cooperative opportunities between those calling for more environmental justice inclusion in mainstream environmental education and those who create mainstream guides. Environmental Justice Indicators are appended. (Contains 4 tables and 6 figures.)