The present study investigates how the acquisition of Mandarin situation-bound utterances (SBUs thereafter) supports the process of Chinese as a second language (CSL) learners’ conceptual socialization and what factors may contribute to the developmental patterns of conceptual socialization. Kecskes (1997, 2003, 2007, 2013) argues that SBUs, as a particular type of formulaic sequences, significantly contribute to the conceptual fluency in a second language. SBUs are highly conventionalized, prefabricated pragmatic units whose occurrences are strongly tied to standardized communicative situations (Coulmas, 1979; Kecskes, 1997, 2000, 2003, 2007; Kiefer, 1985, 1995). They serve as as a particular community’s means for talking about particular subject matters and as a key component of other culturally-authorized activities (Pawley, 2009: 12). They constitute the very core of what would be called native-like idiomaticity (Granger, 2001; Pawley & Syder, 1983). Sociolinguistically, SBUs help create contextual appropriateness (Iswasaki, 2009); linguistically, they help create native-like texture.     The reason why situation-bound utterances are the focus of the study is that they constitute a substantial part of the conceptual socialization of a second language. Second language is acquired through socialization in the target speech community. The acquisition of a second language is a process of acquiring not only linguistic but also socio-cultural knowledge of a given language. Conceptual socialization deals with how novice learners “become competent members of their community by taking on the appropriate beliefs, feelings and behaviors, and the role of language in this process” (Leung, 2001: 2). Since SBUs carry rich information about the socially and culturally appropriate ways of language use, a crucial part of conceptual socialization is learning to put SBUs to use in active and purposeful involvement in interaction. The mastery of SBUs, in return, greatly promotes L2 learners’ grammatical and conceptual fluency. The process of conceptual socialization goes hand in hand with the change of L1-based conceptual system. Qualitative changes in L1-dominated conceptual system are expected to occur “under the influence of the newly emerging language,…(and newly acquired) new strategies, behavior patterns, and socio-cultural knowledge (through the L2 channel)” (Kecskes, 2014: 67).   The focus of the present study is on the relationship between Chinese SBUs and CSL learners’ conceptual socialization. Mandarin Chinese is regarded as a language of an esoteric society. An esoteric society, according to Wray (2008), has a high level of formulacity. This view is confirmed in Coulmas’ (1981) claim that the more tradition-based a society is, the more its members seem to make use of situational formulae. Since China is a highly tradition-based society, there is a large sum of formulaic sequences, especially situation-bound utterances. This study was designed to empirically demonstrate the supporting role of SBUs in CSL learners’ conceptual socialization. The following sections introduce the importance of formulaic language, in particular SBUs in second language acquisition.   1.1 Background to research1.1.1 Formulaic languageIn any society a second language is acquired through immediate and mediated interactions which are governed by a system of rules, conventions, and practices. Here is what Goffman (1967) says:It seems that a system of practices, conventions, and procedural rules comes into play which functions as a means of guiding and organizing the flow of messages. An understanding will prevail as to when and where it will be permissible to initiate talk, among whom, and by means of what topics of conversation. (pp. 33-34)   Rintell & Mitchell (1989) also pinpoint the importance of the rules of language use:No ‘error’ of grammar can make a speaker seem so incompetent, so inappropriate, so foreign as the kind of trouble a learner gets into when he or she doesn’t understand or otherwise disregards a language’s rules of use. (p. 248)Prefabricated linguistic expressions encode a wealth of information about the use of a language, linguistically and conceptually. These expressions abound in everyday conversation. They, along with grammar, gestures, interactional rules, cultural practices, social conventions, etc., are a crucial component of the system of rules, conventions, and practice used to maintain the flow of messages in social interactions. Prefabricated units are also mappings of the rules of language use. They are a means of guiding an individual’s participation in social interaction. They are understood as ‘preferred ways of saying things’ (cf. Wray, 2002) and ‘preferred ways of organizing thoughts’ (Kecskes, 2007, 2013). Wray (2002) proposes ‘formulaic sequence’ as a generic term to refer to a wide array of multi-word strings or frames such as sayings, prayers, proverbs, idioms, social routines, collocations, metaphors, lexical bundles, and multi-word units with open slots “which can be filled subject to varying levels of constraints, community-wide sequences and idiosyncratic sequences” (Weinert, 2010: 2).