The use of computer-mediated communication technology across different countries and cultures is under-investigated in information systems (IS) research. The measurement equivalence issue in cross-cultural IS studies has also not been addressed adequately. This study applies a rigorous structural equation modeling approach (SEM) to compare differences between two groups of college students in the United States and China, by adapting a research model that explains an individual’s use of Instant Messaging (IM). After achieving measurement equivalence across the two groups using SEM, we found that, in their behavioral intention to use IM, Chinese students paid more attention to the effect of perceived enjoyment, while Americans placed more emphasis on perceived usefulness. We found that relationship commitment was more salient in explaining perceived enjoyment for Chinese than for Americans. We also found that the effects of perceived critical mass on perceived enjoyment and perceived usefulness were stronger for Americans than for Chinese. Contrary to our hypothesis, we found that the effect of relationship commitment on perceived usefulness was stronger for Americans than for Chinese. Implications for research and practice are discussed