This research attempts to expose the patterns of language behavior of two five-year old bilingual children through the analysis of the code-switching and code-mixing occurrences in their everyday conversational interactions. The goal of the study is to analyze the code choice and the motivation behind such pattern in order to see whether there are any differences between the two case studies, and most of all, what is causing these differences in linguistic behavior to occur. Data used in analysis was collected during informal conversations recorded in home domain of the two families studied. The recorded data along with the observational notes collected was then analyzed sentence by sentence and separated into several dyads in order to understand the relation between the children‟s code-switching/code-mixing and the interlocutor. It is concluded that most common motivation behind their code choice is solidarity –establishing “we code”, referential, directive, and reactive to positive/ negative face and power. The major difference between the two children‟s language behavior regarding code choice is rather in the patterns of code-switching versus code-mixing. The boy, being a natural bilingual who acquired the second language (L2) simultaneously is more prone to code-switch in certain situations. On the other hand, the girl, who acquired L2 consecutively and therefore adopted the syntax of Serbian language, uses more code-mixing during her conversational interactions. This showed close connection of the linguistic behavior with the linguistic environment exposing essential mechanisms of children‟s ability to adjust their language skills to their conversational needs.