Homophily in networks can arise either from meeting opportunities or from preferences. We use the number of joint classes students have as a measure of exposure intensity to identify the relative contributions of meeting-based and preference-based racial homophily in teenagers’ friendships in US secondary schools. We present robust evidence that friendship increases with exposure, but even more for same-race students. We develop and estimate an intuitive structural model of friendship formation to reproduce and decompose this stylized fact. We find that preference-based homophily explains the majority of overall racial homophily, but that meeting- based one explains more than a third of it. We argue that this still leaves room for policies targeting meetings in order to improve racial integration. We simulate such policies and discuss their effectiveness in increasing meetings, friendships, and reducing segregation at the school level.