The purpose of this study was to clarify the relationship between socio-demographic variables and the variables of children’s emotional intelligence, maternal parenting behaviors, and teacher-child relationship upon children's peer-competence. The study also sought to verify the relative influence of these variables upon peer-competence. The research subjects were sampled targeting 200 children aged from 4 to 5 at 2 kindergartens in Seoul and Gyeonggi Province, as well as their mothers, and the homeroom teachers of the corresponding children. The data were collected by questionnaires and analyzed. Data analysis was conducted by t-tests, Pearson's correlation analysis and multiple regression analysis. The followings were the major findings: first, children's emotional intelligence, maternal parenting behaviors, and teacher-child relationship had a close relationship with peer-competence. For children's peer-competence to be of a relatively high level, competent, children's emotional intelligence, in mothers' genial and encouraging parenting behaviors and limit set, and the formation of a close relationship with the teacher were important considerations. Second, the variables having the greatest influence upon children's peer-competence were shown to be recognizing emotions in others and handling relationships using the children's emotional intelligence. These can be considered to be essential elements in order for children to form and maintain positive peer relations. Accordingly, a teacher will be able to offer a program of promoting peer-competence to children who appear to lack competence in peer relations by developing an emotional regulation program that can help them recognize other's emotion and also help them regulate their own.