Critical thinking is deemed as an ideal in academic settings, but cultural differences in critical thinking performance between Asian and Western students have been reported in the international education literature. We examined explanations for the observed differences in critical thinking between Asian and New Zealand (NZ) European students, and tested hypotheses derived from research in international education and cultural psychology. The results showed that NZ European students performed better on two objective measures of critical thinking skills than Asian students. English proficiency, but not dialectical thinking style, could at least partially if not fully explain these differences. This finding holds with both self-report (Study 1) and objectively measured (Study 2a) English proficiency. The results also indicated that Asian students tended to rely more on dialectical thinking to solve critical thinking problems than their Western counterparts. In a follow-up data analysis, students' critical thinking was found to predict their academic performance after controlling for the effects of English proficiency and general intellectual ability, but the relationship does not vary as a function of students' cultural backgrounds or cultural adoption (Study 2b). Altogether, these findings contribute to our understanding of the influence of culture on critical thinking in international education. (Contains 1 figure and 8 tables.)