This dissertation utilizes the first fifteen years of Pollution Probe’s history (1969-1984) as a prism for examining the origins and development of environmental activism in Canada. The organization was pivotal in the evolution of environmentalist discourse and activism in Toronto, both through its own activities and its role in institution-building. Rooted in Toronto, Pollution Probe provides insight into the early history of the Canadian environmental movement, demonstrating the many ways that this movement differed from the one that took shape in the United States. As will be demonstrated, Pollution Probe was representative of the first wave of Canadian environmental non-governmental organizations [ENGOs] that were formed in the late 1960s and early 1970s. Unlike their American contemporaries, which evolved over a period of decades out of existing conservation organizations, Canadian ENGOs such as Pollution Probe appeared on the scene almost instantaneously. Furthermore, the Canadian organizations tended to be highly localized, in contrast to the larger, national ENGOs found in the United States. While the early Canadian ENGOs originally excelled by virtue of their focus on local pollution problems, the shift to more abstract, underlying problems was met with varying success. Ultimately, they were ill-equipped to address the larger, transnational issues that came to dominate the environmental agenda in the 1980s and 1990s