While many studies globally demonstrate the overall advantage of bilingualism - in particular interms of third language acquisition – these findings are not repeated in Danish schools where bilingualism is often considered a disadvantage. However, third language acquisition has never been studied in the Danish context. Thus, this study investigated plurilingual students’ English proficiency skills (their L3) relative to their monolingual peers’ English proficiency skills in the context of Denmark. The participants were ninth graders from nine different schools in the greater Copenhagen area. The initial results revealed that the monolinguals outperformed the plurilinguals on their general English proficiency skills with huge differences within the plurilingual group. Subsequently, a qualitative investigation was carried out in order to understand these results; here the findings suggest that a multi-dimensional approach is called for, including the students’ response to language teaching practices