This textbook articulates and defends Ecologism - an ideology which has grown from the developing interest in the moral, political, economic and scientific issues centring on human relationships with the environment of the planet. The concept of Ecologism starts from the position that the non-human world is worthy of moral consideration and that this should be taken into account in the ordering of social, economic and political systems. It is recognised as a major development in Environmental Politics and, increasingly, as a significant alternative to existing political philosophies.The book provides a comprehensive and systematic survey of the main components of Ecologism, and examines elements which have been neglected in the existing literature. Written in a clear and approachable style, it covers both the current debates surrounding this key aspect of environmental political philosophy and the author's own development of these debates.