The ways in which we come to know the environment are always inherently political—as are the ways in which environmental knowledge is put to use in the world. Focusing on “scientific knowledge” and “Indigenous knowledge,” on knowledge obtained through work as well as through leisure, the contributions in this volume explore how environmental knowledge is acquired, constructed, and deployed to make political claims on or for the environment. This volume also shows how environmental knowledge is embedded in grassroots, national, and international political efforts to find solutions to environmental problems. These essays showcase examples from Canada and Western Europe, offering insights into how different forms of environmental knowledge and environmental politics come to be seen as legitimate or illegitimate.