Continuing progress in developing empirical information on different facets of long-term care service use has been possible because of improvements in the design of data sets. New generations of data sets are being developed with a recognition of the inherent nature of long-term care. Notably, long-term care implies care received over an extended period of time, thereby presenting numerous occasions for changes in the characteristics of both the services that are used and the recipients of the services. In large part, the design of the data sets has been made in response to research and policy interests in long-term care. This article highlights some observations about progress in the development of long-term care data, and the relationship between policy questions in long-term care and the design of relevant data sets.