PIRLS is an international assessment of reading comprehension at the fourth grade that has been conducted every five years since 2001. In 2011, nationally representative samples of students in 49 countries participated in PIRLS and prePIRLS. Forty-five countries assessed fourth grade students, and some countries participated in one or more of the other available options initiated in 2011 to permit wider participation at the end of the primary school cycle: four countries assessed their sixth grade students; and three countries participated in prePIRLS, a less difficult version of PIRLS inaugurated in 2011 to be a stepping stone to PIRLS. In addition, PIRLS 2011 included nine benchmarking participants, mostly regions of countries that also participated in PIRLS, including three Canadian provinces, two Emirates, the Andalusian region of Spain, and the US state of Florida. Malta and South Africa used benchmarking to collect information relevant to their language of instruction policies. In total, approximately 325,000 students participated in PIRLS 2011, including countries assessing students at more than one grade, benchmarking participants, and prePIRLS. PIRLS 2011 continues the series of significant international studies in reading literacy conducted by the International Association for the Evaluation of Educational Achievement (IEA). PIRLS is directed by IEA's TIMSS & PIRLS International Study Center at Boston College. The students in PIRLS responded to questions designed to measure their reading comprehension across two overarching purposes for reading:Â?Â? Reading for literary experience; and Reading to acquire and use information. The achievement results are reported on the PIRLS scale, which has a range of 0-1,000 (although student performance typically ranges between 300 and 700). PIRLS uses the centerpoint of the scale (500) as a point of reference that remains constant from assessment to assessment. The top-performing countries in PIRLS 2011 were Hong Kong SAR, Russian Federation, Finland, and Singapore. In addition to the four top-performers, Northern Ireland, the United States, Denmark, Croatia, and Chinese Taipei had high average achievement, followed by Ireland and England who also performed very well and rounded out the top eleven high-achieving countries. The US state of Florida and the Canadian province of Ontario also did very well. In general, fourth grade students from many countries around the world demonstrated high achievement in reading. Of the 45 countries participating at the fourth grade, only twelve countries had average achievement below the PIRLS scale centerpoint of 500. Countries assessing their sixth grade students also had achievement below 500, as did the prePIRLS countries (estimated via linking to PIRLS). There was evidence, however, that countries with many very low-achieving students at the fourth grade make substantial gains in reading achievement by the sixth grade. The following appendixes are included: (1) Countries Participating in PIRLS 2011 and in Earlier PIRLS Assessments; (2) Characteristics of the Items in the PIRLS 2011 Assessment; (3) Population Coverage and Sample Participation Rates; (4) Percentage of Students with Achievement Too Low for Estimation; (5) Average Percent Correct in the Reading Purposes and Processes; (6) Percentiles and Standard Deviations of Reading Achievement; (7) Organizations and Individuals Responsible for PIRLS 2011; and (8) Sample Passages, Questions, and Scoring Guides. (Contains 70 exhibits.)