This chapter considers ascetic experience. It provides historical background for the ascetic movement in the early centuries of Christianity and highlights the texts that can serve as sources for the examination of this type of experience. It shows that ascetic experience is characterized by processes of withdrawal and repentance, both physical and emotional, which try to eliminate temptation, combat passions, and purify the heart. This is achieved through practices of vigilance and discernment that involve a close monitoring of emotions and patterns of thought and action. Such practices result in a purification and reorientation of the self that move through self-denial and self-control to transformation. Ascetic experience thus emerges as a way of grappling with the deeply experienced shortcomings of the human condition through processes of abnegation and a radical break with “ordinary” life.