Incarceration changes temporal reality and alters the way prisoners mark time. Simultaneously, their previous methods for marking time become ineffective or injurious to their well-being. Prisoners are caught in a temporal quandary. On the one hand, they do not want to lose track of time, as this bespeaks a stigmatizing incompetence. On the other hand, they also seek to avoid counting standard temporal units (hours, days, etc.), because doing so slows the perceived passage of time during their imprisonment. In this lecture, I examine how prisoners develop distinct ways of marking time as a response to the circumstances of their captivity.