What do children know about communication? In the increasingly globalized world we live in, nowadays children more often come into contact with multiple languages at different ages and in variable contexts. Consequently, they may at times be required to communicate in situations in which they lack sufficient understanding of the language used. In international schools, these exolingual situations of communication are the order of the day. Knowing about communication, that is, being aware of the interaction, of the potential obstacles and of different strategies to overcome them, is essential to bring exolingual situations of communication to a successful end. Are there features of language acquisition that affect the development of this facet of metacognitive awareness? In this thesis a specific aspect of early plurilingualism is examined in detail. Reactions of children who learned a new language at an age and in a context in which they were able to be conscious about their learning are compared to those of children who learned a new language in a less conscious way, from birth onwards. Results demonstrate that a conscious language learning experience is a relevant factor in the development of this aspect of metacognitive awareness in children.