Abstract : This study deals with the sequential organization of language choice and code-switching between Persian as a first language and Swedish as a second language in the process of initiating and resolving a problem of understanding and producing the correct version of a lexical item. The data consist of detailed transcripts of audio tapings of two bilingual students' collaborative writing sessions within the frame of a one-year master's program in computer science in a multilingual setting at a Swedish university. The students, both Persianspeaking, are advanced speakers of Swedish as a second language. For this article, four lexical language-related episodes, where code-switching between Persian and Swedish occurs, are analyzed. The analyzed excerpts in this article are drawn from a corpus of data consisting of language-related episodes identified and transcribed in the audio tapings. We employ a conversation analysis (CA) approach for the analysis of bilingual interaction. This means that the meaning of the code-switching in the interaction is described in terms of both global (the conversational activity at large) and local interactional factors. In the analysis, a close step-by-step analysis of the turn-taking procedures demonstrates how the communicative meaning of the students' bilingual behavior in a lexical episode is determined in its local production in the emerging conversational context and how it can be explicated as part of the following social actions: drawing attention to a problem, seeking alliance when a problem is made explicit and confirming intersubjective understanding when the problem is resolved.