This quasi-experimental study examined the effects of the Promoting Alternative Thinking Strategies (PATHS) Preschool Program on the outcomes of children's social-emotional competence, perceived relationships between teacher and children and teachers' ability to create a positive classroom atmosphere. Two hundred and eighty five children (48-72 months) and teachers in Izmir participated in the intervention, and 280 children (48-72 months) and teachers participated as comparison group. Intervention teachers implemented PATHS in their classrooms. For data triangulation, multiple sources of data were collected in the study. Classrooms were observed using two different scales. Teacher rated students using another two different scales. Children were assessed with an interview to evaluate their perceptions of relationships. Intervention group teachers reported greater improvement of children's social-emotional skills, interpersonal relationship skills and emotion regulation. Furthermore, when observed intervention group children showed higher levels of pro-social behaviour, increased levels of compliance, better problem solving skills and more positive feelings. Intervention group children also described their relationships with their teachers as significantly more positively. Finally, intervention group teachers perceived more dependency in their relationships with children.