Whereas scholars have thoroughly deconstructed the myth that so-called mainstream environmentalism was born of the first Earth Day in April 1970, we have just begun to explore what happened in the decade following. This article provides a much needed intervention into the scholarship on environmental politics in the 1970s by examining the activities of Friends of the Earth (FOE) in its long first decade (1969–1984). Founded in 1969, FOE synthesized concerns with environmental degradation, human welfare, and democracy into an aggressive political agenda. By the mid-1980s, it had replaced its original critique of corporate capitalism and government intransigence with a pragmatic and reformist analysis that held the central form of political action to be a citizen s petitioning of the state. FOE's development during its long first decade demonstrates the deliberate and contentious choices by which mainstream environmentalism emerged as a coherent political practice. While these choices have often been taken as a natural or inevitable response to the Reagan administration s assault on environmental protections, FOE's history demonstrates that these choices were far from inevitable and came at a high cost for mainstream environmentalism's relationship with grassroots political participation.