CLIL programmes have been adopted as the main educational approach in multilingual settings, as is the case of the Valencian Community (Spain). In fact, so as to measure the effectiveness of this approach, considerable research has been conducted comparing the outcomes of CLIL with more traditional non-CLIL contexts (Agustín-Llach 2016; Arribas 2016; Canga-Alonso 2015). However, very little is known about the effect of CLIL on the oral production and comprehension of young language learners whose L3 is English. Therefore, the purpose of this descriptive study is twofold: first, to compare and analyse the L3 primary students’ oral production and comprehension in CLIL science and EFL settings; and second, to determine the effect of CLIL on L3 students’ oral production and comprehension. Results have demonstrated that CLIL programmes in primary education benefit the students’ oral production as they develop the learning and practice of technical language and specific vocabulary related to the content subject, the use of complex grammatical structures, and the students’ oral fluency, confidence and pronunciation. In contrast, we found that non- CLIL learners obtained better results in grammar use, everyday language, accuracy and oral comprehension. Finally, the adoption of a multilingual approach is proposed so as to promote multilingualism in education.