For more than 50 years, the International Association for the Evaluation of Educational Achievement (IEA) has been instrumental in developing an analytical model for understanding the relationships between educational policy (the intended curriculum), classroom and instructional practices (the implemented curriculum), and educational learning outcomes (the achieved curriculum). The "PIRLS 2011 Encyclopedia" describes the intended curriculum in the countries and sub-national jurisdictions that participated in the PIRLS 2011 and prePIRLS assessments, providing a detailed description of the national contexts for the teaching and learning of reading. Each PIRLS 2011 participant contributed a chapter to this volume summarizing the overall structure of its education system, its reading curriculum and instructional approaches, its requirements for teacher preparation, and the types of assessments and examinations that are employed to monitor educational outcomes at the national level. The policy-related information provided in the "PIRLS 2011 Encyclopedia" is intended to complement the data on educational outcomes that are provided in the companion report, "PIRLS 2011 International Results in Reading" (ED544362). This information may be used not only to help understand the relationships among policies, practices, and outcomes within countries, but also to provide potentially powerful insights into international best practice. (Individual sections contain references.) [For Volume 2, see ED544364.]