This cluster-randomized trial examined whether a sustained, multicomponent professional development (PD) intervention delivered at center level could enhance young children's language learning in diverse Early Childhood Education and Care (ECEC) settings in Norway. The initiative combined ongoing coaching for teachers with structured collaboration with parents to support language-rich activities both in classrooms and at home.
The study used a cluster-randomized design. Centers were randomized to receive the PD intervention or to serve as controls. Data collection included a baseline (pretest) assessment and a follow-up (posttest) after the intervention period. The design aimed to evaluate both direct effects on targeted language skills and potential effects on more distal language outcomes.
Data from 887 children were included in the analyses. Children ranged in age from 1.5 to 4 years. The sample was 51% boys and included a high proportion of children identified as dual-language learners (53%). Participants were drawn from 56 ECEC centers located in lower-income, multilingual areas of Oslo, Norway.
The intervention was center-wide and multicomponent, providing sustained coaching for teachers over the study period. A core element was active collaboration with parents to extend language-supportive activities into the home, for example through shared reading. The model emphasized sustainability and embedding language-supportive practices in everyday routines within centers and families.
Assessments occurred at pretest (August to October 2021) and at posttest (May to June 2023), covering an 18-month intervention window. The study distinguished between targeted language skills (those directly addressed by the PD activities) and more distal language skills representing broader language development not explicitly targeted.
After 18 months, children in centers receiving the PD intervention showed a statistically significant improvement in targeted language skills compared with controls (effect size d = 0.19, p < .001). The study did not find main effects for the more distal language outcomes assessed. These results indicate that the intervention produced modest but significant gains on the language domains it directly addressed within the study period.
Analyses reported that most positive outcomes in the intervention group were contingent on the level of implementation adherence. Both classroom-level adherence to the PD practices and uptake of home-based activities with parents influenced children's language outcomes. This suggests that fidelity to the multicomponent model and active parent engagement were important mediators of effectiveness.
The investigators summarize that a long-term, center-wide professional development program with sustained coaching and parent collaboration produced measurable gains in the specific language skills it aimed to improve among young children in diverse ECEC settings. The program operated in lower-income, multilingual areas of Oslo and emphasized teacher support and shared reading at home. Greater use of language-supportive activities in classrooms and increased shared reading at home were associated with stronger outcomes within the intervention group.
The study concludes that multicomponent, sustainable PD models in ECEC can support language learning for young children, particularly when implemented with high fidelity and when complemented by family engagement. The findings highlight the potential value of center-wide PD that includes teacher coaching and parent collaboration in multilingual, lower-income urban settings. The report also notes that effects were observed for targeted skills but not for broader distal language measures, and that local educational practices and center capacity should be considered when interpreting and implementing such models.
This randomized controlled trial is reported in Child Development (2026 Aug 29;97(5):1836–1852) with DOI 10.1093/chidev/aacag065 and PubMed ID 41981765. Authors include Veslemøy Rydland and colleagues with affiliations at the University of Oslo and the Chinese University of Hong Kong. The article is labeled a free article and the authors declared no conflicts of interest.