In this study, we aimed to examine whether five-year-old children with varying first-language (L1) vocabulary skills benefitted differentially from second-language (L2) teacher-led group talk and peer-play talk when acquiring L2 vocabulary in preschool contexts.

The participants were 26 bilingual children, speaking Turkish (L1) and Norwegian (L2), who participated in a longitudinal study. At age five, they experienced variability in the amount and diversity of the L2 talk they were exposed to in interactions with teachers and peers.

Preschool L2 talk exposure was assessed by calculating the density of word tokens and word types in video-taped teacher-led group talk and in peer-play talk. The children’s vocabulary skills were assessed in L1 at age five and in L2 at ages four, five, six, seven and 10, using translated versions of the Peabody Picture Vocabulary Test-III. To obtain a more reliable estimate of the children’s L2 vocabulary skills we used data from all time points to fit a longitudinal growth model.

Children with more developed L1 vocabulary skills who were exposed to teacher-led talk and peer-play talk with a high density of tokens had more developed L2 vocabulary skills at age five. This interaction effect remained after controlling for maternal education.

Few previous studies, if any, have analyzed whether the interaction effects between L1 vocabulary skills and L2 exposure may impact L2 vocabulary skills; that is, whether children with more developed L1 vocabulary skills are more prepared to make use of the L2 environment.

Interdependency among languages may be mediated by classroom talk quality. Rather than limiting the discussion of L1–L2 relations to issues of direct transfer, future research should include children’s experiences with using socio-pragmatic skills when interpreting word meaning.