NOMS is responsible for the prison system in England and Wales. It runs some 130 prisons, which vary considerably in age, type, size and the resources required to operate them. Since 2010, through an estate strategy, NOMS has made major changes to its land and buildings. It has closed some prisons, expanded others and built more on new sites. The rate of change is faster than for decades. This inquiry looks at the value for money of these changes, considering whether they have reduced resource costs and improved quality and performance (in terms of security, safety, decency, and providing 'purposeful activity'). It also examines how estate changes could be affecting the prison system overall and how NOMS, working with other government bodies, could reduce the prison population by managing key offender groups better, including indeterminate-sentenced prisoners and foreign national prisoners.