In the present study, we investigated whether Moroccan- and Turkish-heritage children living in Flanders, the Dutch-speaking part of Belgium, acquire new Dutch vocabulary to the same extent when they are provided with exactly the same type of language input. Turkish-heritage children seem to have significantly lower language proficiency in Dutch, compared to their Moroccan-heritage peers. Previous studies have shown that existing language skills in the second language can affect sequential bilingual children’s vocabulary acquisition in the second language considerably.

The novel word learning of Moroccan- and Turkish-heritage six-year-olds (N = 52) was investigated by means of four dynamic storytelling sessions in which six new object labels and six new action words were incorporated.

The children’s conceptual and linguistic knowledge of the novel words was extensively tested. Six analyses of covariance were conducted, with origin as a between-subjects factor and proficiency in Dutch as a covariate.

Our findings indicate that Turkish- and Moroccan-heritage children acquired the novel words to almost the same extent when their prior language proficiency in Dutch was taken into account. However, Moroccan-heritage children still outperformed their Turkish-heritage peers, producing the novel object labels.

For this study, we used a methodology specifically developed for this age group. In addition, we statistically controlled for the children’s initial proficiency in Dutch, in order to get a better insight in the actual learning processes of new Dutch vocabulary of Moroccan- and Turkish-heritage children.

Our outcome suggests that initial language proficiency in Dutch is an important predictor of novel vocabulary learning. Furthermore, we argue that linguistic properties of the children’s first language may play a role in second language acquisition, suggesting that a different approach to the stimulation of second language (vocabulary) acquisition in minority children of different ethnic origin may be necessary.