The Progress in Reading Literacy Study (PIRLS) was developed to help improve the teaching of reading and the acquisition of reading skills around the world, and was approved by the IEA (International Association for the Evaluation of Educational Achievement) General Assembly as an essential component of the IEA's regular cycle of core studies, which also includes mathematics and science (known as TIMSS). PIRLS is in its third round of assessing reading achievement for students in their fourth year of school. PIRLS 2011 provides countries with the unique opportunity to obtain internationally comparative data about how well their children can read after four years of primary schooling. Countries also will obtain detailed information about home supports for literacy as well as school instruction. For the countries that participated in PIRLS 2001 and PIRLS 2006, PIRLS 2011 will provide information on changes in students' reading achievement. Since PIRLS will continue on a five-year cycle into the future, countries participating for the first time can collect important baseline information for monitoring trends in reading literacy. As a new initiative in 2011, IEA has developed the prePIRLS assessment in response to the needs of the growing population of countries requiring the kind of information provided by PIRLS but whose students are earlier in the process of learning to read than expected by the PIRLS assessment. PrePIRLS, which can be administered to students in the 4th, 5th, or 6th grades, is designed to test basic reading skills that are a prerequisite for success on PIRLS. The "PIRLS 2011 Assessment Framework" is intended as a blueprint for IEA's 2011 assessment of reading literacy. Adapted from the widely accepted earlier version of the PIRLS framework, the 2011 framework resulted from a collaborative process involving many individuals and groups--notably the PIRLS Reading Development Group (RDG) and the National Research Coordinators (NRCs) of the more than 50 participating countries. All told, the framework underwent several iterations in response to the comments and interests of the PIRLS countries and the reading research community, and embodies the ideas and interests of many individuals and organizations around the world. Appendices include: (1) Acknowledgements; (2) Sample PIRLS Passages, Questions, and Scoring Guides; and (3) Sample prePIRLS Passage, Questions, and Scoring Guides. (Contains 6 figures and 4 footnotes.)