How do language learners interact with those who already speak the language they are learning? It is more than just a question of learning vocabulary and grammars – learners also need to learn how to put together conversations in their new language and to vary the way they interact across different contexts. This book shows, using millions of words of data, how this happens. It is the first large scale, corpus-based exploration of the discourse macro-structures in conversational interaction between L1 and L2 speakers, and explores three corpora to show, in spoken interaction with L1 speakers across a range of tasks, the dynamics of discourse construction. Considering factors including cultural background, task and proficiency, it characterises the repertoire of discourse functions used in these interactions and shows how they vary according to a range of variables.