This guidebook was designed by Urban Institute researchers, in consultation with the Annie E. Casey Foundation, to help policy makers, program implementers, and advocates use U.S. Census and other data sources to identify immigrant populations in their communities--their characteristics, their contributions, and their needs. The guidebook discusses national trends in immigration and addresses public policy questions that can be analyzed using these data. It provides users with advice on how to identify immigrants in the data and cautions them on data limitations. The guidebook also includes an analysis of the immigrant population in Providence, Rhode Island, by way of example.