This chapter provides a detailed account of attachment-based psychodynamic psychotherapy and draws upon therapeutic work taking place in two adult male prisons in the UK: a category A (maximum security) prison and a category C prison. Both of these prisons hold life-sentenced prisoners. Those in the category A prison range from people at the beginning of their sentence to people long past their early release date. Those prisoners in the category C prison who have moved from higher secure conditions may be aiming to move to open prison conditions. However, they could also be returned to higher secure conditions if their security classification were to be changed. The crimes committed by men in these prisons vary and include rape, other sexual offences, robbery, murder and other physical violence. Many of these crimes are drug and/or alcohol related; most of the people entering therapy started misusing substances at a very early age, often before leaving primary education. Of particular pertinence to this chapter is the fact that many prisoners have experienced extremely dysfunctional childhoods. Their histories include parental neglect and violence, sexual abuse, physical abuse, witnessing violence against a person they love and having a parent with mental health problems. Unsurprisingly, these problems have often unfolded against a background of personally disruptive lifestyles and early contact with mental health services. Men entering therapy have stated that the prison environment can offer the most stable period of their lives; yet this environment also embodies their worst nightmares. It is paradoxical that, for some, their most stable and secure experiences are those which are also their most feared and despised. Many of the men entering therapy have been recidivist prisoners and have only spent a few weeks of their adult life in the general community. The work detailed in this chapter involves providing individual, weekly psychotherapy to prisoners. Mainly, this is long-term therapeutic work, but sometimes there is a need for brief focal therapy if a prisoner is due for release or transfer in a few weeks or months and is able to work on specific issues. (PsycINFO Database Record (c) 2019 APA, all rights reserved)