This study investigates the concept and role of civil society involvement in the sustainable development process and explores the rationalization for involving civil society participation to facilitate social change, through an in-depth examination of the Earth Charter campaign. Models of civil society developed by The Commission on Global Governance (1995) and the Summit of the Americas (1994) are employed to support this rationale. A history of the Earth Charter campaign and an analysis of the campaign's use of civil society to promote the values and ethics of the Charter are provided. In addition, a summary and analysis is presented of the apparent effectiveness of civil society participation to promote social change within the Earth Charter project. The research for this study is a manifestation of my professional experience at the Earth Council, the Earth Charter International Secretariat, located in San Jose, Costa Rica.