Secondary data analysis plays an increasingly important role in epidemiology and public health research and practice, but many difficulties confront researchers and analysts who wish to use secondary data to address a research or policy question. This practical guide is the only book to provide both an introduction to secondary data analysis and a list of major sources of secondary data in the United States. Entries for each data source include the focus of the data, years available, data collection process used, and directions about how to access the data and supporting materials.