This chapter explores what is gained (and lost) in a sociology of sexuality that applies a materialist and posthuman perspective. It establishes a Deleuze-inspired language of sexuality using the concepts of ‘assemblage’, ‘affect’, ‘productive desire’ and ‘territorialisation’. Sexuality is re-located away from bodies and individuals, on to the affective flow within the sexuality-assemblages of bodies, things, ideas and social institutions that produce sexual capacities in bodies and collectivities. The chapter re-thinks conceptions such as sexual desire, sexual response, sexual preferences, sexual codes of conduct, sexual identity and sexuality itself. The chapter develops and illustrates both this ontology and its translation into a methodology for social inquiry using two disparate datasets to explore the sexuality of young men: a series of interviews with higher education students and two focus groups with white working-class teens.