SUMMARY
This article discusses codeswitching in a community of practice generated by the Languages without Borders Program in a large public university in Southern Brazil. The corpus presented in this article consists of a synoptic chart with the description of 15 events involving at least one English Teaching Assistant (ETA) and has codeswitching as an integral feature, as well as the transcription ofone prototypical interactional event in which codeswitching happens. Ourinterpretation of the data suggests that (1) codeswitching is a central resource in these interactions, and that (2) these interactions seem to culminate in: (a) student teachers practicing and learning English and English-speaking culture from the ETAs, (b) ETAs practicing and learning Portuguese and Brazilian culture from the student teachers. In addition to that, codeswitching seems to be a style that demonstrates engagement in the community.