Cross-linguistic influence and the fluent alternation of several languages have been the focus of interest of recent research (García, 2009; Muñoz, 2007; Safont, 2001). The present study analyzes cross-linguistic influence and language switches in the oral production of English by 25 Catalan-Spanish bilingual children in a Spanish primary school. With that aim, we first identify the most common types of code-switch and their function in an EFL classroom by using Williams and Hammarberg’s (1998) categorization of code-switches. Second, we test the applicability of such model by examining to what extent and in what manner the background languages (L1 and L2) are used during English production (L3) in the context of the Valencian Community, where Catalan and Spanish coexist. The data obtained show that both learners and teachers code-switch into Spanish rather than Catalan during interaction in English, thus assigning Spanish an instrumental role. In line with previous research, we suggest that these results may have been motivated by contextual factors (Muñoz, 2007).