Local language proficiency is often regarded as a key enabling factor for expatriate success. In this study, we use data from the iGOES project to examine how language proficiency contributes to expatriate outcomes. Language proficiency is negligibly to weakly related to most outcomes, but does show positive relations with interaction adjustment. Moderator analyses support the interpretation of this relation as reflecting increased comfort from being able to communicate effectively, rather than reflecting cultural engagement or social inclusion effects. Overall, results indicate that local language proficiency can contribute to expatriate comfort, but is not absolutely necessary for expatriate success.