This proposal outlines a program of research designed to investigate patterns of marital childlessness in the developed and developing countries of the world from the circa-1940 time period to the present. The research project has five specific aims; 1) to describe patterns of marital childlessness in countries where adequate data are available for each of the following time periods: 1940-45; 1946-55; 1956-65; 1966-75; 1976-81; 2) to estimate marital childlessness rates in those countries for those time periods where sufficient data are not available for direct measurement; 3) to set forth and test for the developed and developing countries two separate, although not unrelated, theoretical models designed to account for the variability in marital childlessness; these models will be developed by drawing upon the moderization and socioeconomic development literature; 4) for thjose countries where fertility surveys have been conducted and where the survey results are now available for public use, to employ a decision-tree model to separate out for each country the voluntary childlessness component from the involuntary childlessness component; 5) to conduct subnational studies of marital childlessness in ten selected countries of the world for the circa 1970 time period; descriptive and analytic studies will be conducted at the subnational level for the United States, Mexico and Brazil (the Americas); Portugal, Spain and Poland (Europe); Taiwan, Indonesia and Bangladesh (Asia); and Mozambique (Africa). Within the limits of existing census and survey data and methodologies, this research should yield data and results on, and interpretations of marital childlessness for a larger and more representative sample of populations than ever before.