This paper explores the emergence of collaborative interaction among early secondary learners in bilingual sections at state schools in Andalusia. These sections are organised in line with a content and language integrated learning (CLIL) approach. By transcribing and then analysing data from oral interviews conducted with randomly selected pairs of CLIL learners and mainstream (MS) peers, the article compares and discusses the quantity and quality of collaboration evidenced in turn-taking patterns. In doing so it also proposes a pragmatic, participant-based approach to the initial classification of turns, prior to more functionally aligned analysis. Four initial turn types are identified in the data but while all four obviously contribute to the overall ongoing talk, only two are deemed inherently collaborative. These are embedded turns, where one speaker contributes to another speaker's main turn, and cooperative turns, where two or more speakers jointly construct the message. Once identified, each of these turn types was examined for patterns of functional use. The research finds that the CLIL learners are participating both more frequently and more effectively in collaborative turns than their MS counterparts. In closing we briefly discuss some of the implications of this finding. (Contains 1 table, 17 extracts, and 2 notes.)