One of the first volumes in the new QuadrangLe Social Problems Series, under the general editorship of Bernard Rosenberg, this book sets out to describe the major demographic developments, past and present, in the United States, and to show the various social problems that have arisen as a consequence of these developments. Demography, according to Mr. Stockwell's definition, is ""the science that is concerned with ascertaining the size, composition, and distribution of the population in any given area of human habitation."" it is, in other words, the mathematical end of the sociological Spectrum. There is a good deal more to it than simple head-counting. Demographers provide the bricks with which all other social scientists must build, cud ""demographic variable"" is only clinical short-hand for the political and economic realities we all face. The ""population problems"" in the U.S. may not be as obvious or as dramatic as those in Asia and Latin America, but they are real, and require serious attention. Air cud water pollution, suburbanitis, unemployment, racial tension--all have their demographic aspects, and, one hopes, are amenable to accurate forecast cud thus to some degree of prevention or cure, as we learn to measure them accurately in these terms.