Introduction

We have argued earlier that individual multilingualism is a very diverse phenomenon. Adults and children have different ways of becoming multilingual and developing multilingual competence. At the same time, multilingual language use – which, on the one hand is the outcome of multilingual competence and on the other is the driving force that refines this competence – is determined by a range of factors relating to why, where, how, about what and with whom one is communicating. We have thus concluded that different types of multilinguals and various ways of developing or acquiring multilingualism provide a range of ways to define and classify multilingual individuals. Such a classification is a rather complex task because multilingualism is dynamic – and not only at its inception, since it changes across the multilinguals’ lifespan depending on linguistic needs and opportunities within social and personal contexts. In the previous chapter we laid out the general issue of who is regarded as multilingual, how children become trilingual, the different research perspectives taken in particular studies concerning the development of trilingualism in infancy, and how formal education can generate trilingualism. Unlike the general concepts and ideas underlying Chapter 5, in this chapter we delve into more specific matters concerning the question: how do trilinguals do it (acquire and use three languages)? How can we explain it? What is the evidence we have? Knowledge of the processing and use of languages in trilinguals provides a window to understanding language processing in general and the limits of cognitive capacities where language load is concerned. The multilingual’s lifelong use of different languages and the pattern of mixing or switching between these can be taken as illustrative evidence to distinguish the various types of language behaviour and linguistic competence that are different from monolingual output.