Emergence of mixed-sex friendship groups during adolescence: Developmental associations with substance use and delinquency

Prospective longitudinal data from over 14,000 youth residing in 28 communities in the rural United States were analyzed to examine the emergence of mixed-sex friendship groups in early adolescence. Youth were surveyed on 5 occasions between fall of 6th grade and spring of 9th grade. At each assessment, youth reported the names of up to 7 same-grade friends and described patterns of alcohol use, cigarette use, and delinquency. Approximately 800-900 friendship groups (M = 10.5 members) were identified at each assessment and categorized in terms of gender composition (all-girl, mostly-girl, mixed-sex, mostly-boy, all-boy). The proportion of groups categorized as mixed-sex increased with grade level (10% in 6th grade, 22% in 9th grade), but gender-homogenous groups predominated at all grade levels (76% in 6th grade, 51% in 9th grade). Mixed-sex groups were slightly larger than all-girl groups but the same size as all-boy groups. All-girl groups had the highest levels of tight-knittedness (i.e., density, reciprocity, and transitivity), with mixed-sex groups having the lowest levels and all-boy groups having intermediate levels. After controlling for demographic factors, future mixed-sex group membership was predicted by lower popularity, higher levels of delinquency, and lower levels of alcohol use; mixed-sex friendship group membership was associated with increased likelihood of cigarette use. Results are partially consistent with Dunphy's (1969) classic account of the emergence of mixed-sex groups in adolescence, but suggest that in early adolescence, mixed-sex group affiliation is significantly associated with deviant behavior and peripheral social status, not with popularity.