Youth in modern Western countries grow up in diverse societies. Yet research shows that their friendship networks tend to be segregated along ethnic, racial, and religious lines. Understanding how and why such friendship segregation arises is necessary to eventually promote social integration. Research has shown that the composition and structure of friendship networks can influence the development of a wide range of individual attitudes and behavior. In this chapter, the authors show how social network analysis (SNA) advances our knowledge of the causes and consequences of segregation in youth’s friendship networks. They first highlight competing and complementary theoretical considerations regarding the emergence of friendship segregation...