The "Teacher Education and Development Study in Mathematics" assessed the knowledge of primary and lower-secondary teachers at the end of their training. The large-scale assessment represented the common denominator of what constitutes mathematics content knowledge and mathematics pedagogical content knowledge in the 16 participating countries. The country means provided information on the overall teacher performance in these 2 areas. By detecting and explaining differential item functioning (DIF), this paper goes beyond the country means and investigates item-by-item strengths and weaknesses of future teachers. We hypothesized that due to differences in the cultural context, teachers from different countries responded differently to subgroups of test items with certain item characteristics. Content domains, cognitive demands (including item difficulty), and item format represented, in fact, such characteristics: They significantly explained variance in DIF. Country pairs showed similar patterns in the relationship of DIF to the item characteristics. Future teachers from Taiwan and Singapore were particularly strong on mathematics content and constructed-response items. Future teachers from Russia and Poland were particularly strong on items requiring non-standard mathematical operations. The USA and Norway did particularly well on mathematics pedagogical content and data items. Thus, conditional on the countries' mean performance, the knowledge profiles of the future teachers matched the respective national debates. This result points to the influences of the cultural context on mathematics teacher knowledge.