Early years' immersion education programmes can be either monolingual or bilingual, and their objectives can range from language maintenance and/or enrichment to early second language learning, depending on the context of implementation. Here we examine some of the key issues and policy concerns relating to immersion education in the early years. Among these are difficulties associated with the term itself in certain political contexts, due to historical negative experience. Another issue discussed concerns the differing outcomes noted by studies comparing monolingual and bilingual programmes for minority language children. The importance of training in immersion methodology for early years' educators is discussed, and the need to adapt preschool pedagogical practices to the immersion context, in order to provide optimal input for young language learners. Consideration must also be given to differentiated provision in early years' immersion programmes, with adaptation to the needs of L1 speakers as well as L2 learners, and to children with language impairment. The article explores some of the challenges currently facing this sector, particularly focusing on pre-service and in-service training and professional development for practitioners, and the availability of appropriate materials in less widely used languages. Evidence of the benefits for children and their families of attending a high quality immersion preschool points to the need to review the recognition and resources accorded to this sector by parents, primary years educators and educational planners.