This study investigates the role of proficiency in the acquisition of conventional expressions as a pragmalinguistic resource in second-language (L2) Chinese. One hundred and four undergraduates, including 57 learners of Chinese as a foreign language at 3 levels of university instruction and 47 native speakers completed an aural-oral discourse completion task presented in Chinese. Native-speaker responses show that there are conventional expressions associated with specific situations and learner responses show that learners are increasingly able to produce the expressions as proficiency increases. En route to mastering the conventional expressions, learners develop sociopragmatic competence that allows them to produce the same speech-act and content as native speakers in the same situations, thus creating contexts for the conventional expressions. Interlanguage analysis of learner production also reveals that learners attempt the pragmatically conventional expressions prior to full mastery, using key words of the expressions called lexical cores.