Rather than describe mean gender differences in mathematics across different cultures, this study instead focused on an in-depth item analysis across two countries, the United States and Spain. The purpose of this study was to investigate gender differences on multiple-choice mathematics items across two countries by using the data gathered in the Third International Mathematics and Science Study (TIMSS). Although there were no mean gender differences on the total scores in the United States as there were in Spain, micro-level analysis of item characteristics must be considered when interpreting results. Even within categories, the direction of gender differences varied depending on other characteristics of the item. It was concluded that item difficulty was indeed related to gender differences in both countries. (Contains 50 references.) (ASK)