Friendship similarities in internalizing problems in early childhood

A key factor identified in friendship formation and stability is similarity. Homophily of externalizing problems has been reported frequently, but less attention has been directed at homophily of internalizing problems. Whether young children who are friends resemble each other in their internalizing problems is thus largely unknown. In order to increase understanding of the social risk factors implicated in the etiology of internalizing problems, it is important to establish whether internalizing problems cluster in friendships. The present study examines homophily of internalizing problems while controlling for externalizing problems in a sample of children aged 4-8.Methods: A community sample of 1584 children or 792 dyads with a mean age of 5.85 (SD = 1.26) participated. Of these friendship dyads, 557 were reciprocal and 235 unilateral friends. Internalizing and externalizing problems were reported by teachers.Results: Intraclass correlations were calculated to test for similarities between reciprocal and unilateral friends. Support was found for the homophily hypothesis, in that reciprocal, but not unilateral friends, were substantially similar in their internalizing problems.Conclusions: In reciprocal friendships we found substantial similarity. From these results, we might conclude that homophily is already present in friendships of young children regarding internalizing problems. Theoretical and practical implications of these findings are discussed. (C) 2012 Elsevier Inc. All rights reserved.