The Trends in International Mathematics and Science Study (TIMSS) 2011 is the fifth administration of this international comparative study since 1995 when first administered. TIMSS is used to compare over time the mathematics and science knowledge and skills of fourth- and eighth-graders. TIMSS is designed to align broadly with mathematics and science curricula in the participating countries. The results, therefore, suggest the degree to which students have learned mathematics and science concepts and skills likely to have been taught in school. In 2011, there were 54 countries and 20 other educational systems that participated in TIMSS, at the fourth- or eighth-grade level, or both. This paper is an appendix to the "Highlights From TIMSS 2011: Mathematics and Science Achievement of U.S. Fourth- and Eighth-Grade Students in an International Context" report. It contains the report's standard error tables. (Contains 42 tables.) [For the full report, "Highlights from TIMSS 2011: Mathematics and Science Achievement of U.S. Fourth- and Eighth-Grade Students in an International Context. NCES 2013-009," see ED537756.]