Background: Preschool teachers play a vital role in stimulating young children’s language development (Kim & Yun, 2019). It is widely known that high-quality language interactions in preschool are critical for supporting the language development of children, and in particular for children at risk (European Commission, 2018; Sammons et al., 2015). However, in practice, interactions of a relatively low quality are reported in the preschool classroom in Flanders (Peleman et al., 2019). Furthermore, the quality and quantity of these interactions are even lower with at-risk children (i.e. monolingual or multilingual children with low socio-economic status) that are less familiar with school-relevant language at home. Fostering language stimulation teacher competencies is thus an important focus for preschool teacher education. Therefore, the main goal of this dissertation is to gain insight in the development of language stimulating teacher (LST) competencies in preschool teacher education students. In this study, competencies are viewed as a continuum, as outlined in the adapted model by Blömeke et al. (2015) and elaborated upon by Vanderlinde et al. (2020). In this model, competencies are conceptualized as the interplay between dispositions, situation-specific skills and classroom performance. The focus of the research will be on the situation-specific skill 'professional vision'. Applied to language stimulation (LS), this competency model forms the foundation of the research.

Methods: Three studies are conducted to explore LST competencies' development. Study 1 aims to develop valid and reliable instruments for measuring LST competencies, including a video-based tool and a survey. Study 2 describes the current state of LST competencies using these instruments with 600 student teachers. Study 3 investigates the impact of a blended professional development intervention (PDI) on LST competencies through a quasi-experimental design,.

Conclusion: This research aims to enhance understanding of LST competencies and inform strategies for improving language stimulation in preschool education.

This PhD is part of the broader TACOS SBO-FWO project that runs from 2023 until 2026.