The major findings of a research project on the relationship between population growth and economic development are summarized in this monograph. The study compares recent demographic and economic trends in Japan, Korea, Thailand, and Indonesia to worldwide experience as described by an econometric model of population and development. The study presents evidence that, by reducing their rates of childbearing, the four countries studied have been able to achieve higher material standards of living. Fertility reduction is shown to result in greater expenditures on education, leading to a more productive labor force, higher rates of saving and investment, and populations with greater numbers of people of working age. Contrary to common belief, additional population growth generated by reduced mortality does not appear to reduce standards of living or lower rates of growth of per capita income appreciably. Other issues addressed include: (1) the extent to which declining fertility is an automatic feature of economic development, as opposed to a consequence of population policy and other non-development factors; (2) the importance of investment in population quality as a means of achieving higher rates of economic growth; and (3) the reasons for high life expectancies among East Asian populations. Twenty-four tables and 17 figures present the findings graphically. A 114-item bibliography is included. (JB)