Research repeatedly demonstrates the detrimental consequences of social isolation, but little is known of why adolescents lack social integration. Therefore, the present study uses social network analyses to take a unique look at adolescents’ degree of integration. A total of 317 seventh through ninth graders (13.7 years, 162 girls) out of 18 classes reported friendship patterns and their respective class teachers provided information on students’ social skills. Results showed that social-skill indicators improve with higher categories of integration. Furthermore, in two-level-random-intercept models (L1: adolescents, L2: peer groups), indicators of social skills predicted the degree of integration each adolescent had on both the individual and the contextual level. Findings support the importance of adaptive peer relationships, because the degree to which adolescents are socially integrated in class is not merely related to their own but also to their friends’ social-psychological constitution.