As the number of international students in the United States increases, many researchers show interest in understanding how international students adapt to the local society and what factors influence this process. Cultural identity and language proficiency, as two important factors for international students in adaptation, cannot be ignored. The purpose of this study was to examine the relations of cultural identity to language learning for international students (n = 77) in the United States. In order to achieve this goal, participants completed measures of cultural identity, motivation for language learning, and self-perceived language proficiency. Using path analysis, two important findings emerged. First, ethnic identification was negatively related to self-perceived English proficiency, but this relation was mediated by motivation in learning English (i.e. high levels of motivation for language learning could buffer the effect of ethnic identification). Second, American identification (i.e. feeling a strong attachment to the United States, seeking to learn more about U.S. culture) promoted English proficiency through motivation in language learning.