摘要:The Internet, as the largest worldwide network of interconnected computers, assumes multilingualism and thus deserves to be the focus of the latest research on communication. On the one hand, multilingualism can be interpreted as the use of multiple languages or varieties in a particular situation. Therefore, the authors here speak of multilingualism among Croatian elementary school children on the Internet, especially on Facebook. The first step was to conduct research on multilingualism (including both vertical and horizontal multilingualism) of seventh graders in three counties in the northern and north-western regions of Croatia. The next step was to examine whether elementary school children express their multilingualism (both horizontal and vertical) on Facebook as well. The authors wanted to explore whether code-switching and code-mixing occurred in their communication on Facebook, and if they did, to what extent and for what reasons. The conclusion was that Croatian elementary school students are highly multilingual both with respect to vertical and horizontal multilingualism, which is expressed in their communication on Facebook as well, where they frequently use code-switching and code-mixing.