This book provides a comprehensive analysis of language policy development in Ireland for the inclusion of three languages in the Primary School Curriculum. Using a comparative study of Ireland and Catalonia, chapters provide a theoretical examination of issues related to cognitive language acquisition and European policy regarding language status and use, along with empirical examinations of teacher attitudes to early trilingual education. The book draws from psycholinguistics and sociolinguistics to situate the study within a broader context of European multilingualism and language learning, offering evidence-based directions for social planning issues that affect communities internationally.