This study titled ‘Prison Overcrowding in Nigeria’seeks to extend knowledge and understanding of prison overcrowding through examining the views of Nigerian prisons’ inmates andstaff,including criminal justice institutions and officials. Views explored include participants’ perspectives on overcrowding and whetherit couldbe prevented, as well as coping mechanisms and general response strategies.The research adopts a mixed methods research strategy based on ethnographic fieldwork conducted in Nigeriaas well as interviews, focus groups, questionnaires and secondary data analysis. One hundred and sixty-six individuals drawn from thirteen Nigerian institutions presumedto have experience and knowledge of prison overcrowding as well as Nigeriancriminal justicesystem participated in the study. In addition, observations were conducted at six Nigerian prisons.Key findings unearthed in this study are that prisons in Nigeriaarein constant overcrowding mode irrespective of their design, capacity, and location.Prison overcrowding in Nigeria is a systemic problem rather thanan emergency issue. Prison design capacity is an insufficient and unreliable indicator forunderstanding Nigerian prisonoperation as well as overcrowding. Overcrowding in Nigerian prisons offers profitable opportunities for a number ofindividuals and companies. Nigerian criminal justice institutions lack the capacity to adequatelyrespond to prison overcrowding,andtheattempts by non-state actors to support prisoners inresponse toprison overcrowdingare also undermined by corruption in the system.This study points out that overcrowding in Nigerian prisons is a direct result of past and present Governments’ inaction. Thus, the study advocates that prison overcrowding in Nigeria is preventable and manageable through policy initiatives by the Nigerian stakeholders,particularly the elected politicians.