This issue discusses world population trends and their implications for more and less developed countries. There have been two periods of major population expansion since 1750 with the first lasting almost 200 years and the second surge occurring after World War II. Growth rates in industrialized countries are now very low with fertility below replacement levels. High growth rates persist in sub-Saharan Africa and parts of Latin America and South Asia, but indications exist that these regions will soon follow the world trend toward lower growth rates. The fact that the projected increase in the world population growth will come in less developed countries (LDC) raises the possibility that population growth will restrict efforts to raise living conditions among the LDCs' poorer populations. Organized efforts to increase access to family planning information and supplies are associated with significant increases in contraceptive prevalence and declining fertility in LDCs. Since organized interventions to increase family planning awareness involve basic and often conflicting human values, population policy remains a controversial area. Graphs, charts, black and white photographs, and a 20-item selected bibliography are included. (DJC)