There is a concern in Galicia (Spain) about possible negative effects on academic performance caused by the introduction of CLIL (content and language integrated learning) in schools. It has been said that when three languages coexist in the same context as vehicles of education, it is too much for the students, especially in primary education. In this study, the academic grades of 747 students from 13 primary schools in Galicia were analyzed over two consecutive school years. Data was gathered from students of all ages. The results reveal that the difference in performance for the CLIL and the non-CLIL groups cannot be considered significant; that is, there were no negative effects on academic performance caused by CLIL. Additionally considering the significant number of studies demonstrating the positive effects of CLIL in certain areas, it is concluded that the approach CLIL should be reinforced in schools.