How are two or more languages learned and contained in the same mind or the same community? This handbook presents an up-to-date view of the concept of multi-competence exploring the research questions it has generated and the methods that have been used to investigate it. The book brings together psychologists sociolinguists Second Language Acquisition (SLA) researchers and language teachers from across the world to look at how multi-competence relates to their own areas of study. This comprehe