571 elmentary school children from grade 3 to grade 5 were used as subjects to investigate the relationships among social preference, friendship quality, passive withdrawal, self-perceived social competence and loneliness, and in addition, to investigate the impact of different level variable of peer relations on loneliness. The results indicated that children's peer relations variables(peer acceptance, friendship quality, self-perceived social competence) can significandy predict their loneliness; the predictive effectiveness of self-percei...