Establishing and maintaining positive social interaction with peers is important for young children because it will form a foundation for their later social adjustment and academic achievement. Social competence in this study means an increasing awareness and understanding of other human beings as part of the child\'s world. The purpose of the study was to help four-year-old children to accept other children in their mind. This study had three specific aims: To find the reasons for their difficulties; to examine their changing play behavior; and to observe teachers\' roles in helping them to become involved in peer group play. Lack of communication skills and emotional instability were the main difficulties the children faced. Regarding the changing play pattern, they passed through five distinctive stages: Staying alone, showing strong interest in the peer group play, going voluntarily to friends, actively playing with one or two friends, and finally becoming an active member of the peer play group. In improving children\'s involvement in peer group play the teachers played several important roles: Making them feel safe, giving them an opportunity to experience familiar things, suggesting plays, creating opportunities to become acquainted with other children, and modeling how to play with other children.