Justice Reinvestment is a major movement in criminal justice reform in the US and attracting lots of interest in the UK from both sides of the political spectrum. It is an approach to addressing the penal crisis that looks detail at the causes of offending that result in offenders ending up in custody. In particular, it examines the factors that result in a disproportionate number of offenders coming from certain communities and neighbourhoods and looks to develop more holistic approaches to reducing offending and re-offending that address the totality of an offender career This book looks at the experience of Justice Reinvestment in the US and the challenges that this particular type of holistic, evidence-based, economically driven approach to criminal justice reform will pose in the UK. It unpacks the economics ideas that underpin it as well as examining the key methodologies that are used in its implementation and the implementation challenges that Justice Reinvestment has raised in the US and will raise in the UK.