This book shows why political theorists must take account of ecological concerns as part of their core enterprise, and how they can do so. It mounts a challenge to the received wisdom, of political theorists and their ecological critics alike, that specifically ecological values go against human interests. In Part I, Hayward criticizes those accounts of ecological values which appeal to nature's 'intrinsic value' or advocate a 'non-anthropolocentric' ethic. Such appeals are bound to fail, he argues, not because their moral impulse is too demanding but because 'values' unrelated to human interests are conceptually incoherent. Insisting on them is politically counterproductive. Part II reveals how it is actually in humans' interests to integrate ecological concern into political institutions and policies. Following a nuanced discussion of 'self-interest', Hayward goes on to show how some ecological problems can be solved by harnessing humans' rational self-interest to market-based and fiscal policies, and others by using more enlightened interests in the provision of social goods. The argument regarding ecological problems that affect non-humans more directly than humans is that humans have an interest in self-respect and integrity which provides reasons to respect non-human beings and their environmental interests. The concluding chapter indicates how the articulation of ecological values in terms of interests makes it possible to integrate them into a political theory of basic social institutions. This book will be of interest to students and scholars in political theory and environmental studies.