There is a concern in Galicia about possible negative effects on academic performance caused by the introduction of CLIL in schools. It has been said that a context where three languages coexist as vehicles of education 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, for two consecutive school years. Data was gathered from students of all ages. The results tell us 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. If we consider as well that there is a big number of studies demonstrating the positive effects of CLIL in some areas, the conclusion is that CLIL should be reinforced in schools.