Similarity of Friends Versus Nonfriends in Adolescence: Developmental Patterns and Ecological Influences

This study examines developmental change across adolescence in the similarity of friends versus nonfriends. This differential in similarity is a key aspect of the organization of the peer context of development: The stronger the correlation between friends for an attribute, the more the attribute delineates clustering and divisions of friendships. We investigated change in the correlation between friends across 12 attributes covering demographics, orientations to key institutions (family, school, religion), and problem behavior, and we expected that the link between similarity and friendship would increase during adolescence for most attributes other than gender. We also predicted that the social ecological factors of school size and attribute variability would be associated with stronger correlations between friends and partially mediate developmental change. Data are from two grade cohorts of 27 small school districts, followed from sixth through 11th grades (N = 454 time-specific networks and over 65,000 person/waves of data; 84.2% White, 6.8% Hispanic/Latino, 3.2% African American, 1.3% Asian,.5% Native American, 3.9% other or multiple). The data analysis takes the form of a three-level random effects meta-analysis of network level correlations between friends (Moran’s I). As expected, declining dominance of gender was offset by the emergence of moderate correlations across a broader profile of attributes. The ecological opportunity factors of grade cohort size and attribute variability significantly mediated these increases in correlations between friends, accounting for 23 to 73% of age-related change for 10 of the 11 attributes other than gender.