While large literatures have separately examined the history of the environmental movement, government planning, and modern economics, Pricing the Priceless triangulates on all three. Offering the first book-length study of the history of modern environmental economics, it uncovers the unlikely role economists played in developing tools and instruments in support of environmental preservation. While economists were, and still are, seen as scientists who argue in favour of extracting natural resources, H. Spencer Banzhaf shows how some economists by the 1960s turned tools and theories used in defense of development into arguments in defense of the environment. Engaging with widely recognized names, such as John Muir, and major environmental disasters such as the Exxon Valdez oil spill, he offers a detailed examination of the environment, and explains how economics came to enter the field in a new way that made it possible to be “on the side” of the environment.