A recent approach to multilingualism is the Dynamic Model of Multilingualism (DMM), which applies the Dynamic Systems Theory (DST) to multilingualism (Herdina, Jessner, 2002; De Bot et al., 2007; Larsen-Freemann, Cameron, 2008; Aronin, Jessner, 2015). The DST is an open system dependent on a number of social and psychological factors. Within a multilingual system, language systems are highly interdependent as they interact with, influence and change each other. According to the DMM, multilingualism is not stable but fluctuating, and the development of multilingualism can not only be positive, but it can also manifest itself as language attrition or language loss. Both positive and negative patterns of development are influenced by the perceived communicative needs of the language user and are thus socially and psychologically interrelated. In the DMM, the M-factor (multilingual factor) refers to the set of skills and abilities developed by a multilingual language user based on his/her previous linguistic and metacognitive knowledge (Jessner, 2008a: 275). The basic element of the multilinguality factor is multilingual awareness, which refers to the awareness of metalingual and interlingual languages and is considered a key factor in multilingual learning and use (Jessner, 2006, 2008a, 2014). Metalinguistic awareness refers to the language user’s ability to see language as an object, to think about language in abstract terms, and to manipulate language as a consequence (Jessner, 2006: 42). Interlinguistic awareness is the awareness of the relationships between languages, which is expressed implicitly or explicitly in language use (Jessner, 2006: 116). Multilinguals have the advantage of metalinguistic awareness.