In a bilingual context, the mother tongue plays a key role in a child's social and personal development, in education and in second-language learning. There is a complex relationship between these three areas. Support for children receiving education through a second language is often in the form of additional learning opportunities in the second language. However, first-language competence has been shown to affect learning in the second language. This paper looks at pre-school migrant children in a bilingual context and investigates the nature of the children's bilingualism. Findings show that they do not have the same level of mother-tongue competence as children brought up in their country of origin. The paper goes on to consider the reasons for these differences in mother-tongue competence and possible responses. The paper concludes that for these children, nursery education in the mother tongue could raise levels of competence in the second language and increase wider educational opportunities, as well as contributing to mutual respect, social cohesion and harmony. There is a complex relationship between mother-tongue development, children's self-esteem, educational opportunities and second-language learning. This paper considers how this complex relationship affects groups of children in four European contexts: Turkey, Norway, Germany and Austria. (Contains 2 tables.)