The politically relevant behavior of scientists in the formulation of public policy by the United States government from 1945-68 is studied. The following types of policy issues are treated: science, space, weather, weapons, deterrence and defense, health, fiscal and monetary, pollution, conservation, antitrust, transportation safety, trade and balance of payments, agriculture, transportation, foreign aid, disarmament and arms control, foreign policy, organization (of government), social, and extraction (of natural resources). Factors influencing the likelihood of scientists' influence on the executive branch of government are developed in Part I of the study. Part II deals with the relationships of scientists and other sectors of government that are likely to develop in the future and discusses ethical questions that arise from scientific research, including the relationship of scientists to different political and religious systems. (AL)