After considering the historical roots of environmentalism from the 1890s through the 1960s, Gottlieb discusses the rise and consolidation of environmental groups in the years between Earth Day 1970 and Earth Day 1990. He examines the increasing professionalisation of the major environmental organizations and the parallel rise of community-based groups over the past decade, and ends with an in-depth consideration of the role of ethnicity, gender, and class in the formation and definition of movements.