The "TIMSS 2011 International Results in Mathematics" summarizes fourth and eighth grade student achievement in each of the 63 countries and 14 benchmarking entities which participated in TIMSS 2011. The report includes trends in mathematics achievement over time for participants in the previous TIMSS 1995, 1999, 2003, and 2007 assessments, as well as student performance at the TIMSS International Benchmarks. Achievement results also are presented for mathematics content and cognitive domains. The "Mathematics Report" provides a rich array of information which describes the educational contexts for mathematics, including home environment support, students' backgrounds and attitudes toward mathematics, the mathematics curriculum, teachers' education and training, classroom characteristics and activities, and school contexts for mathematics learning and instruction. The following appendices are included: (1) Countries Participating in TIMSS 2011 and in Earlier TIMSS Assessments; (2) Characteristics of the Items in the TIMSS 2011 Mathematics Assessment; (3) Population Coverage and Sample Participation Rates; (4) Percentage of Students with Achievement Too Low for Estimation; (5) Average Percent Correct in the Mathematics Content and Cognitive Domains; (6) The Test-Curriculum Matching Analysis--Mathematics; (7) Percentiles and Standard Deviations of Mathematics Achievement; and (8) Organizations and Individuals Responsible for TIMSS 2011. (Contains 145 exhibits and 5 footnotes.)