Research using longitudinal data from the developed world has demonstrated the value of panel surveys for understanding an array of fundamental questions in social science. Long running panels from developing countries, however, are few and far between. The Indonesia Family Life Survey (IFLS) is one such survey, and it has been valuable resource for researchers interested in low income settings. To date we have collected three full rounds of data, in 1993, 1997, and 2000. All are in the public domain, and in combination have proved highly useful with regard to enhancing our understanding of important economic, demographic, and health behaviors and outcomes in a low-income setting. We propose to conduct a fourth full round of IFLS in 2006. The value added of a fourth round is substantial. IFLS4 will extend the time frame the study spans to a full 13 years. The proposed data will greatly facilitate the study of demographic, health and socioeconomic change pertaining to the elderly over the life-course, across generations and over a period of time that includes long-run economic growth, sharp economic downturn and recovery. Being able to assess the impacts of a major economic downturn over a longer period of time (8 years subsequent to the shock) makes IFLS unusual among panel surveys. Having panel data over a 13 year period will allow study of how aging processes work over time for the same individual. It will allow a more thorough understanding of a major health transition that is now underway in Indonesia;in which the roles of chronic diseases, overnutrition and associated health risk factors among prime-aged adults and the elderly have increased in importance;at the same time that problems of infectious disease and undernutrition are still quite prevalent. EFLS4 builds on a very well-developed set of questionnaires from past IFLS surveys. We will also introduce several innovations. We will add several new measures to the already innovative set of physical health measures collected in past waves. We will also develop modules for the community-facility surveys that allow assessment of how decentralization has affected the quality, price and availability of services.