This paper suggests that a dynamic systems theory (DST) provides an adequate conceptual metaphor for discussing multilingual development. Multilingual acquisition is a nonlinear and complex dynamic process depending on a number of interacting factors. Variability plays a crucial role in the multilingual system as it changes over time (Herdina & Jessner, 2002). A number of studies on multilingualism have shown that there are qualitative differences between second and third language learning and that these can be related to an increased level of metalinguistic awareness. From a DST-perspective, metalinguistic knowledge and awareness of this knowledge play a crucial role in the development of individual multilingualism.