As the 21st century begins, most programs in early care and education have not yet integrated peacebuilding strategies into their preschool settings, although conflict resolution programs are finding acceptance in schools. While a growing body of literature on social and emotional learning points to the advantages of early exposure, research-based models for the preschool educator are lacking. This study focused on the key role of the teacher in facilitating conflict resolution in Head Start. The study assessed changes in teachers' conflict knowledge, attitudes, and behaviors after a training intervention that exposed them to theory and practice of conflict resolution, violence prevention and peace education for young children. The study also measured the impact of training four- and five-year-old children in interpersonal problem solving based on the I Can Problem Solve (ICPS) model. The methods were mixed; a qualitative design addressed teachers' changes and a quasi-experimental test measured children's problem solving abilities. Six Head Start teachers participated in a 40-hour college course, received pre-post interviews, and completed a self-assessment of conflict style (Thomas-Kilmann Conflict Mode Inventory). The children in classrooms of the six experimental teachers were trained for approximately two months using the ICPS model. 37 experimental and 27 control group children were tested for problem solving ability using the Preschool Interpersonal Problem Solving Test (PIPS). Findings demonstrate an expanded understanding of conflict and improved use of conflict resolution strategies. Teachers reported an increased level of comfort with handling conflicts after the course. In addition, they reported changes in the way they involved themselves in children's conflicts. Instead of using directive strategies to resolve the issue for the children, after training they used more questioning strategies which centered on helping the children to think of ways to resolve the conflict. Results of the PIPS showed that children who were trained in conflict resolution could resolve interpersonal problems better than children who were not trained. In addition, trained children were better able to come up with non-forceful solutions to a peer conflict than were the control children. The study extends research on appropriate models for preschool conflict resolution and contributes to teacher development and peace education policy.