This paper draws on social capital theory to discuss the way social class plays out in the friendships of teenage students. Based on data from individual interviews and focus groups with 75 students in four London secondary schools, it is suggested that students tend to form friendships with people who belong to the same social-class background as them. Social-class "sameness" is considered to be an element that importantly exemplifies the quality of their friendships, and hence close, inter-class friendships were significantly less common than close, intra-class ones. In addition, class differentials were evident and often reproduced by students, even in the context of the rarer inter-class friendships. This paper concludes that social class is of continuous importance in teenagers' lives and despite some agentic negotiation of class boundaries, as in the case of omnivorousness, students' friendship networks are dynamically informed by class inequalities.