Some multilinguals use code-switching, which involves swapping between languages. In many cases, code-switching is motivated by the wish to express loyalty to more than one cultural group, as holds for many immigrant communities in the New World. Code-switching may also function as a strategy where proficiency is lacking. Such strategies are common if the vocabulary of one of the languages is not very elaborated for certain fields, or if the speakers have not developed proficiency in certain lexical domains, as in the case of immigrant languages.