In Samburu District, northern Kenya, men and women crafted collective belonging through and around colonial stereotypes of their ethnic sexuality. If administrators, missionaries, development workers, and journalists long invoked promiscuity and adultery to describe them as radical Others, rural Samburu turned to ritual to transform the implications of such stereotypes. In ceremonies called lopiro, they sought to end everyday adultery within particular generations and reimagine moral forms of collective belonging to age sets, clans, the state, and a world beyond Kenya. These ceremonies synthesized contradictions between the concrete socioeconomic and political struggles of rural Samburu families and the haunting colonial paradigms of their sexual alterity. Lopiro ceremonies demonstrate the central role of sexuality to autochthonous and ethnic forms of belonging in the postcolonial world.