This study aimed to clarify and deepen the knowledge on and understanding of the role that teachers' practices during teacher-led learning sessions play in creating and enhancing social life in Finnish preschool classrooms. Observational data pertaining to 20 preschool teachers were analysed according to the principles of thematic analysis. Four identified themes reflected teachers' contribution to social life in preschool classrooms in relation to their practices under different group compositions: (1) managing children's peer relations; (2) promoting the coherence of the group; (3) supporting an individual child as a part of the group; and (4) discussing friendship and respectfulness. As a conclusion, the four themes indicated two aspects of teacher support provided for social life: managerial/organisational and emotional. The findings are useful for raising teachers' awareness of the importance of social life, especially when transitions to new educational contexts are timely.