This volume collects empirical studies applying Conversation Analysis to situations where second, third and other additional languages are used. A number of different aspects are considered, including how linguistic systems develop over time through social interaction, how participants 'do' language learning and teaching in classroom and everyday settings, how they select languages and manage identities in multilingual contexts and how the linguistic-interactional divide can be bridged with studies combining Conversation Analysis and Functional Linguistics. This variety of issues and approaches clearly shows the fruitfulness of a socio-interactional perspective on second language learning.