By conducting usability testing on a multilanguage Web site, this study analyzed the cultural differences between Taiwanese and American users in the performance of assigned tasks. To provide feasible insight into cross-cultural Web site design, Microsoft Office Online (MOO) that supports both traditional Chinese and English and contains an almost identical interface design between the two language environments, was investigated. The results indicate that no substantial difference in the use of MOO existed between Taiwanese and American users. Both groups tend to use the search function to find information and locate unknown functions, and did not the menu directly. Moreover, the Taiwanese and American users exhibited similar interface design and color preferences when using the Web site. However, differences in user preferences regarding the motion elements and style of the buttons were apparent. Suggestions for cross-cultural Web site design and the direction of future research are discussed in this work.