Teenage friendships are not just extracurricular; they’re the single most important relationships in a teen’s world. Likewise, a teenage social circle has its own culture, with shared values (hanging out), goals (to amass as big and cool a group as possible), and ways of communicating (Facebook).

One Saturday night this summer, we came upon a party at North Avenue Beach, where we met a loose group of 20 or so kids from Lane Tech, Evanston Township High, Whitney Young, Taft, and other schools. Curious about how they knew one another, we charted their relationships. Here, an anthropological look at a 14-year-old’s Saturday night. Start anywhere.

Photography by Sergio Silva