Nine reports published in this volume reflect a few of the challenges that must be faced by city dwellers in the tasks of controlling the erosion of the quality of city living and saving the urban environment from a final crisis. Reforms necessary to meet the changed conditions are discussed through the following topics: population growth and patterns of change in the population; megalopolis problems and proposals; prevalence, sources, and control of violence in American life; local government modernization, private enterprise in city rebuilding, welfare reforms, black pride, rising concern and the shape of threats to the environment as well as action to protect it; and the new-town movement and concept of city planning. (BL)