This introduction presents an overview of a key concepts discussed in the subsequent chapters of this book. The book claims that the distinction usually made between the 'political' and 'religious', although analytically useful, does not in fact represent the lived experience of Muslim environmentalists or religious people more generally. It examines the relationship between Islamic faith and practice and environmental activism for Muslim environmentalists. The book discusses six Islamic environmental organisations– two in the United States and four in Great Britain, three of which were active at the time of the research, and three of which had recently taken 'sabbatical' from active organising. It gives as detailed an explanation as possible of Muslims involved in environmentalism: their motivations for participation, their understanding of environmental crises and solutions, and the ways in which they utilise their Islamic faith in their activism. The book refers various social movement theorists and concepts and in particular make use of framing theory.