The aim of the present contribution is to investigate similarities and differences of strengths in science competences between countries, based on TIMSS 2003 data. Analyses are based on systematic investigation of patterns of p values for individual science items. Hierarchical cluster analysis was applied to establish meaningful groups of countries. The resulting pattern of how countries cluster together into groups of increasing size is presented and discussed. The features for each group of countries are described in terms of relative strengths according to item format, subject domain, and cognitive domain. Finally, the measures on relative strengths in subject domain were compared to the relative emphases in the intended curriculum and in the implemented curriculum (percentage of topics taught in the classroom). It turned out that the data on emphases in the classroom could explain more of the relative strengths and weaknesses than the intended curriculum.