A kaleidoscope of how citizens in the United States have been answering the question, "What can the average citizen do to protect and enhance the environment?" is presented in this bulletin. Voluntary citizen organizations, environmental organizations, interested individuals, and educational groups are pictured as having combined to fulfill a watchdog role, exerting pro-environmental influence on public opinions, the press, industry, and the government. The scope and impact of their influence is demonstrated by several examples of their undertakings. In addition, the role of private citizens in the environmental quality movement in three American cities (Pittsburgh, San Francisco, Chicago) is described in more detail. It is concluded that citizen activities are an outgrowth of rising public awareness and understanding of environmental problems and of public frustration with the pace at which government and industry have moved to solve these problems. Working within established systems, citizen action groups have helped to focus public opinion on the environment. This case study was prepared by the U. S. Environmental Protection Agency for submission by the government of the United States of America in response to an invitation from the Secretary-General of the United Nations Conference on the Human Environment. (BL)