TIMSS focuses on effectively measuring educational achievement in mathematics and science at the fourth, eighth, and sometimes 12th grades. In addition, TIMSS Advanced measures advanced mathematics and physics achievement in the final year of secondary school across countries. TIMSS Advanced data have been collected internationally three times, in 1995, 2008 and 2015. The United States participated in TIMSS Advanced in 1995 and 2015.

The study is designed to capture the breadth and richness of these subjects as they are taught in the participating counties. The study collects detailed information about curriculum and curriculum implementation, together with empirical information about the contexts for schooling. It therefore provides countries with a much-needed means of improving mathematics and science learning outcomes for students worldwide. In addition, because the IEA has conducted the assessments every four years since 1995, interested parties worldwide can identify trends in achievement and other relevant indices across time.