Code-Switching is a phenomenon in which ¿speakers rely on juxtaposition of grammatically distinct subsystems to generate conversational inferences¿ according to Gumperz (1982:97). The broad use of code-switching in diverse contexts and with at least two languages in contact has made this linguistic device be one of the most studied behavioural features of bilinguals¿ speech (Gregori and Alcantud.2011). Additionally, code-switching, seems to have an important communicative function, that is why it is a very interesting aspect of sociolinguistics to be researched.Nowadays, the development of educational provision is reaching more and more social strata. This fact, together with a wider use of new technologies and globalization, has ¿served to accentuate our sense of a visibly and audibly multilingual modern world¿ (Milroy and Muysken 1995:1). One of the consequences of this modernization has been the incorporation of second languages in the subject syllabus at earlier and earlier ages and, as a result, some new ways of communication are being created from this contact between two or more languages; this is the case of second languages acquisition. When children are in contact with second language teachers, code switching is one of the natural devices they use in order to communicate. In fact, the ¿equivalence constraint on code-switching may be used to measure degree of bilingual ability¿ (Poplack 1980:581). It is thus the objective of this article to analyze in which situations code-switching is exactly used inside a second language acquisition language beginners¿ classroom. To achieve this objective, I selected, recorded and analyzed a class composed of four-year-old Spanish monolingual children in their first days of English classes in order to study the use that both the teacher and the students made of code-switching. The most remarkable conclusion drawn from the present study is that code-switching is used, on depart of both, the teacher and the students in a very high percentage to call beginners attention and to make communication and language learning easier.