This study is based on a Delphi study on environmental literacy which is an important part of science education. The main goal is to clarify the framework, including concepts, contexts, and competencies of environmental literacy, and to reach consensus on this framework in accordance with expert opinions. This study used a mixed method research design, which included both qualitative and quantitative methods, to reveal expert opinions. The exploratory sequential design, one type of mixed method research, was used in this Delphi study and performed in three consecutive steps. The sample consisted of 45 experts who initially agreed to participate in this study, with 20 of the 45 participating in the first step Delphi. The numbers of participants in the second and third Delphi steps are 44 and 31, respectively. This study concluded there was a consensus about the definition, sub-dimensions, and competencies of environmental literacy and the institutions, social groups, and people responsible for the development of qualified environmentally-literate individuals. Additionally, there was agreement concerning what to do to support the development of environmental literacy, topics that should be included in the curriculum and textbooks, and teaching methods and extra-curriculum activities for the development of environmental literacy.