This chapter synthesizes current knowledge about the neuroscience of relationships. Although there are challenges to forming successful relationship, this chapter begins with the premise that humans, like other species, are wired to form, and benefit from, social connections. The chapter defines social neuroscience and discusses the research methods neuroscientists use. In recent decades social neuroscientists have begun contributing to a better understanding of the neurobiological substrates of close relationships (e.g., by unraveling their specific networks in the human brain). Early research focused on love including not only specifying what brain areas are recruited during a behavioral task, but also, specifying when and in what specific combinations they are activated. Social neuroscientists have also examined types of love and types of social rejection (e.g., loneliness as well as social and romantic rejection). The chapter concludes with current challenges facing social neuroscientists and directions their work could profitably pursue.