Published: September 5, 2018

Download: Life Course Centre Working Paper: 2018-15


Deborah A. Cobb-Clark, Colm Harmon, and Anita Staneva.

Non-Technical Summary:

Parents who raise their children bilingual are often concerned that children exposed to two languages are confused and unable to separate the languages, and this could entail a delay in their cognitive development. Underlying this concern is the belief that dual language learning in early childhood places additional burdens on language development in comparison to the acquisition of a single language.

In this paper we examine whether – conditional on other family inputs – bilingual children achieve different outcomes in language and emotional development. We take advantage of the longitudinal structure of the UK Millennium Cohort Study (MCS) data to investigate how the bilingual gap evolves from early childhood to adolescence. We relax the usual assumption that the production function underpinning child development is not itself a function of the age of the child and estimate the bilingual gap in children’s language and emotional development as a cumulative process that depends on current and past endowments of cognitive and non-cognitive capacity.

We find that, based on age-specific analysis, younger bilinguals have lower levels of language development but by age seven they now have an advantage, and by age 11 bilinguals are back to having lower language development than their monolingual peers. Controlling for lagged outcome test scores in an attempt to reduce the bias caused by omitted past inputs, along with a rich set of time-varying controls, we find that on average there is no bilingual gap in language development. In terms of emotional development, our analysis suggests that past bilingual status is associated with fewer difficulties. We find some variation in the impact with the benefit to emotional development larger for boys and children of lower educated parents. There is a stronger persistence in emotional development than language development, but overall persistence in outcomes is quite low (<0.5).

Ultimately, the most important finding is that overall bilingual children are not significantly different when compared with their monolingual peers in language development, taken together with the positive effect of bilingualism on emotional development. With the arguments promoting language acquisition in school from a relatively young age as a means to promote economic competitiveness and growth, the lack of any gap in language and emotional development for bilingual children is key.


September 5, 2018