This article is an introduction to the international assessments Programme for International Student Assessment (PISA) and the Trends in International Mathematics and Science Study (TIMSS) and a review of results from 2003. International comparisons, especially in the media, have elevated interest in science education and stimulated discussions about teaching practices that will contribute to college preparation and workforce skills for the 21st century. Several insights and reflections on international assessments are also discussed. (Contains 9 figures.)