This workshop developed a new, comprehensive, research-based framework for assessing environmental literacy. By bringing together, for the first time, experts in research, assessment, and evaluation from the fields of science education, environmental education, and related social science fields, this project accessed and built its work on the literature and the insights of many disciplines. The North American Association for Environmental Education (NAAEE) worked with the leaders of the only two large-scale assessments of environmental literacy used in the U.S. to date (Programme for International Student Assessment [PISA] and the National Environmental Literacy Assessment [NELA]) to conduct the workshop. The project leaders analyzed PISA and NELA and used a multi-disciplinary search and review of the literature to prepare a draft framework. At the workshop and thereafter, a diverse array of invited experts critiqued that draft and provided suggestions for revision. Then, the leaders/organizers produced a final Environmental Literacy Framework and disseminated it both electronically and at a nationally advertised event to a wide audience of assessment specialists, funding and policy-making agencies, and organizations working to develop assessments and achieve environmental literacy. Many institutions and agencies have noted the need to create an environmentally literate population, and government and private entities are investing hundreds of millions of dollars in projects aimed at enhancing environmental literacy. Given the scope and scale of these investments and the interest in this arena on the part of federal agencies, professional organizations, and corporations, assessments for gauging our progress in transforming our preK-12 education system to achieve that end are needed. The new Framework for assessing environmental literacy provides a foundation for measuring the extent to which we are enabling all learners to acquire the knowledge, skills, dispositions, and behaviors vital for competently making decisions about local, regional, national and global issues.