In this "blue-sky" effort to rethink humanity's basic challenges, Philip Morrison and Kosta Tsipis--both eminent scientists with deep expertise in arms control issues--sketch the broad outlines for a global approach to the problems of security and development. Their goal is to set priorities for feasible action, and their focus is threefold: war and particularly the continuing dangers of nuclear weapons, population and the promotion of increased levels of human well-being, and the threat of environmental degradation.Although their topics are global, the authors focus on the actions of the United States. In their discussion of nuclear options, for example, they argue that reducing American military expenditures can be a catalyst for lowering the world's nuclear risk, establishing a policy of "common security" in response to conventional war, and freeing resources that will allow substantial steps toward "common development." In their discussion of human needs, the authors emphasize the fact that the rate of annual growth in the world's population peaked between 1967 and 1970 and has declined steadily ever since; we can therefore now project what the near steady-state level might be. This topping off of population growth should give us a new baseline from which to address both development and environmental issues.