The Progress in International Reading Literacy Study (PIRLS) is an international comparative study of the reading literacy of young students. PIRLS studies the reading achievement and reading behaviors and attitudes of fourth-grade students in the United States and students in the equivalent of fourth grade in other participating countries. The study began in 2001 and is administered every five years. To provide comparative perspectives on trends in achievement in the context of different education systems, school organizational approaches, and instructional approaches, PIRLS also collects background information from the teachers and school administrators. AIR’s experts provide technical and analytical support for U.S. participation in PIRLS, including consultation and management support; technical review of statistical reports, data files, and data documentation; expert analysis; technical support for the development of web-based data tools and other products; and training outside researchers to use PIRLS data files and other survey resources.