This is an application for a five year competing renewal of a Population Research Center Core Grant to the Center for Demography and Ecology (CDE). CDE is a multi-disciplinary faculty research cooperative for social scientific demographic research whose membership includes sociologists, rural sociologists, economists, epidemiologists, and statisticians. The present application requests funds for the continued support of the Center's infrastructure, including the Administrative, Data Processing, Data Library, and Print Library cores; a new Geographic Information Analysis Core; and, within the Administrative Core, funds to support a new program initiative on Comparative Family and Household Research. Current and planned research and training activities at CDE cover a broad range of demographic issues, but there is an especially large volume of work on population composition and distribution within the United States. CDE activities include research projects for which we seek approval to use CDE cores. In addition to these projects, CDE has NICHD support for predoctoral training in population, predoctoral and postdoctoral training support from the National Institute on Aging (NIA) and a continuing annual supplement to the Center grant from NIA to support new research initiatives in the demography of aging. Many CDE members have overlapping memberships in cooperating research and training units, which include their several academic departments, the Institute on Aging, the Institute for Research on Poverty, the LaFollette Institute for Public Affairs, the Applied Population Laboratory, the population and health program in the Department of Preventive Medicine, the University of Wisconsin Survey Center, and the Social Systems Research Institute. CDE continues to be successful in renewing, expanding and adding breadth to its research portfolio--in its stock of research data and analytic resources and tools; in the number, magnitude and diversity of funded research projects housed at the Center; and, most important, in its ability, through the evolving interests of members, to address significant empirical, theoretical, methodological, and practical issues in population studies. Continued core support from NICHD, in addition to financial support received from the University of Wisconsin and other sources, will enable CDE to continue to perform its mission of facilitating demographic research by providing basic infrastructure services and facilities; an intellectually stimulating environment that encourages and promotes research activities at the frontier of scientific investigations; and a nurturing environment for training the next generation of scholars.