This study treated a key relationship in the developmental ecology of adolescence, friendships, as multidimensional and context specific. First, it examined 4 characteristics of friends (academic achievement, alcohol use, emotional distress, and extracurricular participation) as independent factors and as components in holistic friendship group profiles. Longitudinal analyses of 9,224 adolescents (ages 12-20) revealed that multiple characteristics of friends predicted adolescent behavioral problems, as did membership in the best adjusted group profile. Second, the study examined whether the associations between friendship factors and adolescent behavior varied as a function of the larger peer network and school context, finding that network centrality, school academic press, and intergenerational bonding in schools conditioned the role of friends' characteristics and group profiles in positive and negative ways.