In Content and Language Integrated Learning (CLIL) contexts, the Foreign Language (FL) is used as a vehicular language to learn other school disciplines, and children learn the FL driven by the need to use the language for real communicative purposes (Snow, 1990). However, very little is known on the actual effectiveness of these pseudo-immersion programmes, as most investigations conducted so far have focused on CLIL vs. non-CLIL peer comparisons where CLIL students have received more exposure than non-CLIL ones precisely due to their participation in CLIL programmes, and there is a dearth of research designs which attempt at isolating the variable CLIL. This study comes to fill this gap by focussing on oral production, one of the linguistic aspects which may benefit most from those teaching methods fostering the use of the language in meaningful contexts (Block, 2003). The present investigation assesses oral production in FL English by 15 year-old secondary school children who have received the same amount of English exposure but differ in terms of their participation in a CLIL programme. One of the groups has experienced regular English lessons where the FL is the subject of instruction itself whereas the other group has received 25% of their exposure through CLIL as a consequence of their engaging in using English as a vehicular language from the beginning of secondary school (age 12). English learners were audio-recorded while telling a story in English and their productions were assessed by means of two types of analysis. Firstly, a holistic assessment by trained judges focused on linguistic aspects such as pronunciation, vocabulary, grammar, fluency and content. Additionally, a quantitative analysis was conducted to explore the amount and density of learners’ productions as well as the compensation strategies that they used. Results from the holistic assessment indicated that CLIL learners obtained significantly higher scores in all the linguistic scales analysed except for pronunciation. With regard to the quantitative assessment, analyses showed that CLIL and non-CLIL learners produced stories with similar word counts. However, CLIL learners’ discourse was made up of significantly richer and denser contributions, as attested by their significantly higher scores in the ‘words per turn’ and ‘utterances per turn’ CHILDES ratios. Additionally, CLIL learners were found to resort to compensation strategies such as ‘native language transfer’ or ‘interviewer help demand’ to a significantly lesser extent than non-CLIL learners. These findings could be interpreted as CLIL learners being more capable when communicating in the FL and hint at the benefits of CLIL, a ‘more natural’ learning approach, on oral production skills in FL English. Block, D. (2003) The Social Turn in Second Language Acquisition. Edinburgh: Edinburgh University Press.Snow, M. A. (1990) Language immersion: An overview and comparison. In A. Padilla, H. H. Fairchild and C. M. Valadez (eds) Foreign Language Education: Issues and Strategies (pp. 109-126). Newbury Park, CA: Sage.