The TIMSS 2011 International Results in Science 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 science 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 science content and cognitive domains. The Science Report provides a rich array of information which describes the educational contexts for science, including home environment support, students' backgrounds and attitudes toward science, the science curriculum, teachers' education and training, classroom characteristics and activities, and school contexts for science learning and instruction.