The Commission was instructed to project the probable future trends of population in the United States, to examine the implications of these trends, and to inquire into “... the various means appropriate to the ethical values and principles of this society by which our Nation can achieve a population level properly suited for its environmental, natural resources, and other needs." The preceding volumes have presented the Commission's ! research on population trends and their consequences, and its research on population distribution policy. The present volume presents the Commission's research on population growth policy.

Population changes take place through births, deaths, migration, and the interaction of these with the aging process. The aging process is inflexible-we get one year older every year. Births, deaths, and migration are changeable, but death is outside the realm of population policy in a democratic society. Individuals wish to postpone death, never to accelerate it, and society acts accordingly. Hence, death, or rather its postponement, is the subject of health policy, and is excluded from the realm of population policy.

Migration is variable and is, furthermore, manipulable. Policies affecting internal migration within the United States were the subject of Commission research the results of which are presented in Volume V. The demographic aspects of immigration and emigration were analyzed in Volume I; but, aside from the descriptive information on immigration policy obtained from Federal agencies, the research program of the

Commission included no policy papers specifically addressed to this subject. In this volume, only "Ethics, Population, and the American Tradition" by the Task Force on Ethics and Population treats immigration policy. In any event, the available information about emigration and about the social and economic impact of immigration is so scanty that the value of any such research would have been limited.

Fertility, therefore, is the dominant topic of the policy papers-an appropriate emphasis, given the dominance of fertility in this country's present population growth equation-but it is not the only one. The Commission's policy views as reflected in its Report were of two kinds: "activist" in the sense of searching for measures desirable in their own right which would have the demographic consequence of minimizing future population growth, and "accommodationist" in the sense of acknowledging the inevitability of substantial future population growth and the necessity for doing a far better job of providing for it than we have done in the past.

Accommodation in this sense is no easy task as indicated, for example, by the Commission's anxieties over the ability of inherited structures of local government to manage the affairs of large metropolitan communities. Two papers in this volume assisted the Commission in developing its approach to the problems of living with population change. They are discussed below under the heading "Guiding Population Change."