This research proposes that certain personal characteristics of teachers (attachment security, sensitivity, emotional regulation) influence the quality of the teacher–child relationship, which in turn may play a mediating role in the socio-emotional development of kindergarten children. Although the literature has documented the role of children’s characteristics, few studies have examined teachers’ affective and relational variables in connection with the relationship and children’s socio-emotional development. This project adopts this innovative perspective by integrating these factors into a single explanatory model.

Twenty-six preschool teachers from two regions of Québec (Canada) participated in the study. Each teacher selected a representative subsample of children from their classroom (N = 105 children).

Structural equation modeling revealed that the quality of the teacher–child relationship, as measured by the Student–Teacher Relationship Scale, serves as a mediator between certain teacher characteristics and children’s socio-emotional development. More specifically, full mediation effects were found between teachers’ attachment security - and in particular, sensitivity to the abandonment dimension, relationship quality, and three indicators of children’s socio-emotional development assessed using validated measures: emotion regulation (Emotion Regulation Checklist), social competence (subscale of the Social Competence and Behavior Evaluation), and global socio-emotional functioning (Ages and Stages Questionnaires: Social–Emotional). Full mediation was also observed between teachers’ own emotion regulation, relationship quality, and the same three outcomes.

These findings highlight the direct contribution of certain personal characteristics of teachers to the quality of their relationships with children, and indirectly, to children’s socio-emotional development. They underscore the importance of supporting teachers in developing their own socio-emotional competencies in order to foster those of their students. This is a key issue, not only for teachers’ professional well-being but also for the quality of their pedagogical practices with children.

Keywords: Teacher characteristics, relationship quality, socio-emotional development, kindergarten children.