Prisons in England and Wales have seen a massive increase in the number of elderly male inmates, which is often referred to as the graying of the prison population. The observations offered in this article are drawn from the findings of a large research project studying older prisoners that was begun in 2002. The main argument presented by the author is that elderly prisoners are subjected to institutional thoughtlessness insomuch as they are subjected to the typical prison regimes with little reference to the needs and sensibilities created by their advanced age. Data are drawn from intensive fieldwork in 4 English prisons that involved sustained observations of prison life and in-depth interviews with more than 80 prisoners between the ages of 65 and 84 years. Findings suggest that some degree of institutional thoughtlessness is evident in most prisons in England and Wales. Evidence of institutional thoughtlessness was found in prison exercise rules as well as in health care and access to mental heath services. The author calls on researchers to continue investigations into institutional thoughtlessness in prisons with regard to elderly prisoners, especially considering their increasing numbers in prisons around the world. Notes, references