ABSTRACT This study explores the impact of CLIL (Content and Language Integrated Learning) on the development of listening skills in English both in Primary and Secondary Education in Spain. To do this, CLIL (n=2,790) and non-CLIL learners (n=17,070) enrolled in the 4th grade of Primary Education (9-10 years old), and CLIL (n=2,680), and non-CLIL students (n=17,638) in the 2nd year of Secondary Education (13-14 years old) were compared regarding their oral comprehension skills. Results showed no differences between CLIL and non-CLIL groups in Primary Education, while in Secondary School, the CLIL group significantly outperformed the non-CLIL group in the overall results of listening and in every oral comprehension subskill evaluated, and differences were higher in the most complex listening tasks. These findings seem to suggest that CLIL programs are more effective to promote the acquisition of listening skills in the target language in secondary than in primary school settings. The age of students, along with other contextual differences between the CLIL programme in Primary and in Secondary School might explain these results.