Adopting a social network perspective entails acknowledging the interpersonal context within which close relationships develop. The present chapter covers the recent surge in social network research, and highlights the influence that our friends, families, and acquaintances – both online and offline – have on the initiation, maintenance, and deterioration of romantic relationships and friendships. We begin with coverage of fundamental terminology and theory, and then move to a discussion of evidence supporting the integral role of network members in fostering and nurturing our connections with others. We also address how social network influence can have a dark side (e.g., maintaining toxic relationships, sabotaging existing unions). On a general level, the work reviewed provides overwhelming evidence of “the social network effect,” that is, the power of social networks in shaping social relations. Interpersonal networks provide the support, information, opportunities, and structural embeddedness that often facilitate the initiation and maintenance of personal relationships and tend to impede their dissolution. We conclude with suggested future directions regarding the intersection between social network science and romantic and friendship ties. After all, in our increasingly global society, understanding the consequences of this broadening web of interconnections will become ever more important.