We propose to carry out a fourth round of survey data collection with a sample of about 5,400 American women and men. Participants-most of whom will be between the ages of 60 and 80 at the time of their in- person interviews in 2010-are randomly selected sisters or brothers of individuals who graduated from Wisconsin high schools in 1957 and who have been followed ever since. The combined "graduate" and "sibling" data-supplemented with interviews of graduates'and siblings'spouses or widows and a variety of administrative records-form the core of the Wisconsin Longitudinal Study (WLS). [The strengths of the WLS as a resource for studies of midlife and aging lie in its longitudinal scope, its exceptional sample retention, the broad content and quality of survey and administrative data, and its relational design. It has successfully followed a large and socioeconomically diverse sample from high school graduation (and before) to the retirement years, and it tracks social and economic relationships among the graduates and their significant others: parents, children, siblings, nieces and nephews, and high-school friends. No other large-scale, longitudinal study has all of these features. A 2010 round of contacts with siblings will greatly enhance the unique scientific value of the WLS as a resource for research on health and aging.] We request support for two- hour personal interviews, cognitive and performance assessments, and self-administered leave-behind (or mail) surveys of the WLS siblings. Surveys will replicate and extend content appearing in previous waves of the WLS and will also contain innovative content modules that will further enhance the analytic value of the data. Participants were previously surveyed by telephone and mail in 1994 and 2005;a highly stratified random subset of about 2,100 was also interviewed by telephone in 1977. Considering the age of many of the participants, we will conduct proxy interviews for members of the sample who are not currently able to participate directly. The data collection activities proposed here (for the siblings) and elsewhere (for graduates, spouses, and children) will complement other WLS data collection activities that are already in progress. These include: obtaining large, stable samples of DNA from graduates and siblings;regularly linking to Medicare/Medicaid records and to the National Death Index;and interviewing survivors of deceased graduates and siblings (widows or widowers, children, and siblings) on a continuous basis. All WLS data will be released to the research community-either directly or through a secure data enclave, consistent with high standards of protection for the privacy and confidentiality of research participants-as soon as they have been collected, cleaned, and documented. The WLS is unique as a large scale longitudinal study of adults and their families across more than half a century, and its continuation will support a broad, inter-disciplinary agenda of research on social, psychological, biological, and economic factors in health and aging. PUBLIC HEALTH RELEVANCE: The current round of data collection for the Wisconsin Longitudinal Study (WLS)-which includes this application to collect and analyze another wave of data from siblings of the primary respondents-is designed (1) to provide high quality longitudinal data on health and aging and (2) to facilitate a broad array of multidisciplinary research on the determinants of health and well-being of older women and men. We intend and expect that our new data, along with the rich data presently available from the WLS, will inform public policy in an era of increasing individual responsibility for health and well-being in the retirement years.