Sustainability is the integration of ecological, social, and economic approaches to ensuring healthy local and global communities for present and future generations. Although environmental science and social studies teachers have assumed primary responsibility for sustainability related programs and initiatives, whole school approaches to teaching and learning about sustainability are emerging in K-12 schools (green schools) all around the world (Henderson & Tilbury, 2004). Whole school and whole systems approaches to sustainability not only teach about sustainability via the curriculum but also encourage the school community to become a vibrant place for together learning how members might live more sustainably. Recent research highlights the importance of school leaders and leadership for successful green schools (Birney & Reed, 2009; Higgs & McMillan, 2006; Pepper & Wildy, 2008; Schelly, Cross, Franzen, Hall, & Reeve, 2010). The purpose of this article is to propose a theoretical framework that integrates democratic and ecological principles for describing, explaining, and predicting a continuum of development from more traditional schools to green schools. It ends with suggestions for future research. (Contains 2 figures, 2 tables, and 2 notes.)