Whether language shapes cognition has long been a controversial issue. The present research adopts a functional approach to examining the effects of language use on personality perception and dialectical thinking. We propose that language use activates corresponding cultural mindsets, which in turn influence social perception, thinking, and behavior. Four studies recruited Chinese-English bilinguals (N = 129 in Study 1, 229 in Study 2, 68 in Study 3, 106 in Study 4) and used within-subjects and between-subjects design, written and behavioral reports, and self- and other perceptions. The four studies converged to show that Chinese-English bilinguals exhibit higher dialectical thinking and more variations in self- and observer ratings of personality when using the Chinese language than when using English. Furthermore, dialectical thinking predicted more self- and other-perceived variations in personality and behavior across bilingual contexts. These results highlight the important role of culture in understanding the relations between language and cognition, and attest to the malleability of personality perception and dialectical thinking within and across individuals in response to culture-related linguistic cues.