NIA has entered into a contract with the NAS Committee on National Statistics to learn about methods for combining data from RCTs and observational studies that could potentially offer more definitive analyses than either method alone. NIA supports several observational studies on older populations covering many social and behavioral research domains including the Midlife in the United States (MIDUS), the National Social Life, Health and Aging Project (NSHAP), the Wisconsin Longitudinal Study (WLS), the National Health and Aging Trends Study (NHATS), and the Health and Retirement Study (HRS). NIA has fostered the development of a collection of international data sets based on the HRS in Europe, Asia, and Latin America to exploit cross-national differences to study questions such as the impact of retirement on cognition and health. NIA also supports quasi-experimental research examining large program changes or interventions such as the expansion of Medicare to cover prescription drugs and Medicaid expansion via lottery in Oregon. NIA seek expert input on how to maximize the utility of this unique collection of data assets that focus on aging populations with RCTs as well as natural experiments for social and behavioral research in aging ? a relatively narrow scope for this exploratory planning meeting. For example, our observational data (as is or with minor additions) could improve external validity of RCTs focusing on aging populations and can help better focus plans for experiments or interventions.