In different parts of the world, there are children who learn two or more local languages as well as a national language. In parts of India, Scandinavia, Africa and Asia, there are many trilingual and multilingual children. In some parts of the world, trilingualism is a normal and natural thing.

There is little research on trilingualism and multilingualism in the family to provide clear advice. However, in Canada there has been research on children becoming trilingual in English, French and Hebrew (and in English, French and an indigenous North American Indian language). In mainland Europe, there are many children who become fluent in three languages (e.g. Swedish, Finnish, English; German, French, English). The Scandinavians seem particularly experienced and successful in producing trilingual children. Many Scandinavian children learn two languages in school (e.g. English, German) as well as being fluent in their home language. Language learning has relatively high status in Scandinavian countries. In parts of Africa, Asia and India, trilingualism is also relatively frequent and accepted. Trilingualism is possible and valuable.

One documented route to trilingualism is parents speaking two different languages to their children at home. The children then take their education through a third language. The majority language of the community will influence the relative strength of the three languages. Proficiency in the three languages will change over time. Stable trilingualism seems less likely than stable bilingualism. Establishing trilingualism early on is slightly easier than successfully maintaining trilingualism over the teenage years.

Some parents of trilingual children find it valuable when one or both parents are also learning a new language. While this parent may not be a perfect language model for the child in that new language, nevertheless it sends out an important message to the child, that multilingualism is an important value in the family. While there is always a danger of such a parent teaching errors to the child and the child modelling incorrect forms, the child will become aware that acquiring a new language is part of valued life-long learning and part of family life.

One proviso about trilingualism is that at least one language needs developing fully. It is important in a child's cognitive development that at least one language develops at age-appropriate levels. For example, the child will need sufficient language competence to operate in the increasingly abstract nature of the school curriculum. A slight danger is a low level of development in all three languages. This would impede the child's cognitive development and requires extra vigilance, extra commitment and thoughtfulness within the family.