Learning a foreign language is not merely about learning vocabulary and grammar, but also learning about concepts and intellectual skills that are transferable to one's first language. Many authors seem to think that this is mostly related to metalinguistic abilities which, during early childhood, seem to be closely linked to later literacy competences, including reading and writing. Indeed, Cummins explains through his CUP theory that these skills are "linked and interdependent" (1976) for additive bilingual subjects, who have a high proficiency in both of their languages. The present study explores whether these advantages could also be seen in monolingual children who learn a second language at school in the pre-literacy years. If this is the case, how does the second-language learning influence and help develop first-language abilities and literacy? Is it possible to easily develop a method for children in all types of schools, especially in a monolingual education? This article explores how this could be effective and how one could apply this easily in any setting. It uses a case-study currently taking place in Paris, France, following 38 French-speaking children for two years from age 5 to age 7. After one year, of both qualitative and quantitative assessment, early results show that after one school year of 45 minutes of ESL per week, 5 to 6 year old children's literacy skills seem to have increased compared to children who did not have any ESL classes.