The 28-day menstrual cycle experienced by contraceptive pill-users is a sociotechnical convention that is being questioned as sex hormones are repackaged and administered continuously to reduce the number of periods. Hormonal menstrual suppression proposes that women “choose” if and when to menstruate. Mapping the class and gendered distribution of the prescribed and improvised hormonal regimes adopted by people in Bahia, the introduction examines the relation between self-improvement, control, hygiene, biomedical citizenship and the Brazilian project of modernity. It introduces the stark differences that mark Brazilian health care and argues that the appropriation of bodily plasticity is an integral aspect of the ways in which social hierarchies of race, class or gender are renegotiated in Bahia. The chapter sets the scene ethnographically and methodologically and maps out the book’s objective which is to examine the unwritten cultural scripts that accompany and shape sex hormones use in Brazil.