In his book The Ascetic Imperative in Culture and Criticism (1987), Geoffrey Harpham argued that asceticism is a fundamental instrument in cultural formation and transformation.1 Any narrow identifi cation of asceticism with a set of restrictive behaviours distinctive of delimited historical periods and particular geographical areas misses the general character of the phenomenon. Even if it exists in all cultures, it does not correspond to any one particular sort of religious experience or set of beliefs and practices, concerning for example the superior value of the soul over the body, or the withdrawal from society (Valantasis 2008). Ascetics may challenge their culture, be integrated within it, transcend it, live in tension with it or transform it (Mitchell 1996). Asceticism may therefore be seen as corresponding to a truly transcultural ‘imperative’, which can nonetheless be grasped only through the specifi c forms, motives, contexts and behaviours in which ascetic activity takes place. Michel Foucault came close to this notion when he defi ned ‘practices of the self’ as ‘models that he [the subject] fi nds in his culture and are proposed, suggested, imposed upon him by his culture, his society, and his social group’ (Foucault 1997a: 291). His history of subjectivity can be seen as a genealogy of ascesis. This chapter draws inspiration from such genealogy by seeking to contrast and compare the ascetic practices of antiquity with contemporary bioascesis and to spell out the main elements of the latter. This approach should serve to highlight continuities and discontinuities and thereby to investigate historical specifi cities: it will often be the case that the same practices serve different goals and processes of subjectifi cation.