The knowledge, that the human brain has the faculty of multilingualism, is no result recently revealed by the picture giving processes of the modern brain research. It is simply a matter of fact, shown through everday life. (Nevertheless impressing is indeed the visualizing of the three-dimensional network systems which embed languages in the brain.) Also the knowledge, that languages are learned (and also forgotten) in early childhood age most easily, is not at all a new research result. So, if modern brain research may provide an original contribution in promotion of multilingualism or not, is not a so important question at this moment. The bottom line is the well-known fact, that promotion of language acquisition / learning should be realized in a motivating environment. This is an old pedagogical task. The modern brain research confirms the fact that the only one ideal language acquisition method does not exist. Since language acquisition / learning is realized on individually shaped different ways. To promote multilingualism in a person requires the knowledge of his / her individual language biography. This can be described by the so-called Laswell-formula. To shaper the focus onto the language learning group of grown-up persons, the best language learning method exists in conscious making. This method is not only related to the foreign language but also to the differences between foreign language and mother tongue and thereby to the special features of the mother tongue itself. However the degree of consciousness related to the mother tongue is usually very low. Translation with its two main methods, i.e. documentary and functional translation, is also a very use- and helpful language learning method in grown-up persons. Since it makes conscious of the differences in semantics and syntax of the related language pair. Especially functional translation as one type of intercultural communication further makes conscious of the differences in communication situations between source and target language.