This article discusses the limitations and advantages of using ›asceticism‹ as a universal category and as a hermeneutic tool in the study of late antique religious life and comparative studies of religious communities. It first explores the roots and the history of the terms ›asceticism‹, ›Askese‹ and ›ascétisme‹ arguing that they originate from early modern scholarly traditions rather than being based on the language of late antique and early medieval Christian texts. A second part traces the origins of the term askēsis in Greek monastic discourse, using the Vita Antonii, the Historia Lausiaca, Theodoret's Historia religiosa and the Greek and Latin versions of the Vita Pachomii as case studies. I argue that Athanasius of Alexandria's decision to use askēsis as a key term of his monastic program was motivated by limiting the range of appropriate religious practices rather than praising what we might call radical asceticism. Askēsis took on a life of its own and attained various meanings in Greek monastic texts but never found an equivalent in Latin monastic language. The third part describes the diversification of ›ascetic‹ practices and ideals in a number of Latin hagiographic and normative texts. I question to what extent it makes sense to consider religious practices emerging in the West (following a rule, unconditional obedience, humility, enclosure, sexual abstinence, liturgical discipline, etc.) as forms of Western ›asceticism‹ and argue that using ›asceticism‹ uncritically carries the danger of obfuscating nuances, diversity and transformations of religious practices in the Latin (but also in the Greek) world of Late Antiquity and the early Middle Ages.