A growing number of countries are developing or reforming pension and health policies in response to population ageing and to enhance the welfare of their citizens. The adoption of different policies by different countries has resulted in several natural experiments. These offer unusual opportunities to examine the effects of varying policies on health and retirement, individual and family behaviour, and well-being. Realizing these opportunities requires harmonized data-collection efforts. An increasing number of countries have agreed to provide data harmonized with the Health and Retirement Study in the United States. This article discusses these data sets, including their key parameters of pension and health status, research designs, samples, and response rates. It also discusses the opportunities they offer for cross-national studies and their implications for policy evaluation and development.