Population growth and resource depletion are discussed. The need is stressed for policy makers to understand how population projections relate to the carrying capacity of the earth's basic biological systems. Because the earth's resources are limited, it is essential that policy makers in developed and developing nations be able to analyze the relationship between population and resources such as fisheries, forests, croplands, and grasslands. Economic and social stresses have already resulted in over-fishing, over-grazing, shrinking forests, urban slums, unemployment and, since 1974, annual double digit inflation. One major constraint to unlimited population growth is the oil supply. Petroleum is the principal fuel that powers the global economy. The changing petroleum supply necessitates not only vigorous conservation programs but also establishment of policy priorities which will assure adequate oil supplies for essential purposes such as food production. Population policies which have been devised to deal with population growth include family planning assistance and controls on rural-urban migration. The conclusion is that policy makers must devise ways of stabilizing population at a level far lower than currently projected in order to avoid deterioration of the earth's biological resource base and of the living standards of more and more people. (DB)