Background: Speech and language therapists (SLTs) are increasingly engaging in school-based interventions targeting children with language difficulties. Collaborative work between teachers and SLTs has shown to be beneficial in fostering language development in all children. Both groups of professionals have different but complementary roles in offering language support, according to children's needs. Effective collaboration between SLTs and teachers requires both parties to understand their roles and practices in schools. However, little is known about language support practices in Lebanese preschools and the roles of SLTs in these contexts. Aims: (1) To explore the perceptions and reported practices among preschool teachers (pre-KTs) to support language development; (2) to investigate the current practices of SLTs in preschools; and (3) to understand pre-KTs' and SLTs' perceptions of the SLTs' role in Lebanese preschools. Method & Procedures: Using a quantitative method, the study reports the results of two questionnaires (one for pre-KTs and one for SLTs) that were developed based on a review of the academic literature and adapted to the contextual realities. Questionnaires were completed in hard or soft copy by pre-KTs and through an online survey by SLTs. Outcomes & Results: The questionnaires were completed by 1259 out of 1442 pre-KTs from 175 Lebanese preschools, and by 200 out of 391 SLTs from across Lebanon. First, the findings show that both professional groups recognize they have a role in supporting language development. Second, differences in reported practices were identified regarding language strategies for children with communication needs. In particular, pre-KTs reported less use of specific language strategies targeting children with language difficulties, while SLTs reported that their practices in schools remain primarily focused on children with communication needs. Finally, the analysis of perceptions showed a lack of acknowledgement of the SLTs' role in the prevention of communication and language disorders among all children. Conclusions & Implications: This study provides an overview of the perceptions and reported practices of language development support in Lebanese preschools. The majority of SLTs and pre-KTs acknowledge their role in supporting language development. However, the slight differences in perceptions of SLT roles in prevention interventions highlight the necessity for SLTs to promote their active involvement in services targeting all children. Future research will investigate how SLTs are beginning to reconceptualize their role in intervention for preschool children. This will help to better define SLTs' roles and responsibilities in educational settings and foster effective professional collaboration.