Publication - Research and analysis

What Works to Reduce Reoffending: A Summary of the Evidence

Published: 8 May 2015

This is an updated version of the original review entitled ‘What Works to Reduce Reoffending: A Summary of the Evidence’, published in 2012.

What Works to Reduce Reoffending: A Summary of the Evidence


What Works to Reduce Reoffending: A Summary of the Evidence was prepared in 2011 to support the development of the Reducing Reoffending Programme led by the Justice Directorate in the Scottish Government. This review was intended to be a work-in-progress, to be updated with additional material in the future. The 2014 update represents the first iteration of this process, conducted to support strategic thinking about how best to achieve National Outcome 9 of the Scottish Government's National Performance Framework - 'We live our lives safe from crime, disorder and danger' - and in particular to support the Reducing Reoffending programme.


The aim of the review is to present the evidence into the effectiveness of different approaches to reduce reoffending among young people and adults.


The following presents a literature review summarizing the findings of relevant literature into 'what works' to reduce reoffending. This includes research into the process(es) by which individuals stop offending, and the impact of the criminal justice system on these processes. As such much of the focus of the paper is on individuals and how the criminal justice system can help individuals to stop offending. The review did not consider studies that assessed the effectiveness of criminal justice interventions in achieving outcomes other than reduced reoffending, such as increased public confidence in the criminal justice system and justice to victims. Where available, information on value for money of interventions is provided. The term "desistance" is used extensively in the paper and refers to an extended period of refraining from further offending[59]. However, there is considerable disagreement among researchers about how long an offender must be crime-free before being considered a 'desister', with some researchers claiming that 'true desistance' can be determined with certainty only after offenders die. In most evaluations, a two-year follow-up period is used to differentiate desisters from recidivists.

As a number of researchers propose that there are important differences between the process of desistance for men and women[60], the paper also includes discussion of 'what works' with women offenders throughout.

The review draws heavily upon some key sources of research from Scotland, the rest of the UK and other countries. These fall into three broad types:

  • systematic reviews of "what works" to reduce reoffending,
  • one-off quantitative evaluations of reoffending rates of programme participants and control groups, and
  • a variety of desistance studies, many being observational or explanatory rather than experimental in design, and not focusing on interventions. Methods include longitudinal designs, mixed methods, and qualitative studies exploring offenders' own accounts of the desistance process and the factors that facilitated or hindered a sustained abstinence from offending.

Using both qualitative and quantitative research provides a more rounded answer to the different facets of the question of 'what works', such as why an intervention is believed to have worked[61]. As there is no simple answer to the question of 'what worked' for a particular intervention, using different kinds of evidence is important to inform policy. It is also important to note that there can be problems generalizing the findings of international studies to Scotland, especially if the studies were conducted in countries with very different policies, institutions or offender populations. As a result this review focused wherever possible on research conducted in Scotland, and where researchers have suggested that there may be problems generalizing findings from international studies, this is noted in the review.

The original literature review was updated in 2014, with the aim of including research published since 2011. The first step in identifying relevant texts was to compile a list of relevant authors on the topic of reoffending. This was achieved by examining the bibliographies of existing literature reviews on reoffending (including the 2011 version of this document), criminology conference proceedings and Ben Matthews' own PhD research. Online searches for these authors' most recent work found 308 articles which, to some degree, considered the topic of reoffending. Short time-scales meant it was not possible to include all of these texts in the 2014 review. Through an initial reading of titles and abstracts, the texts were prioritised based on where research was conducted (with a focus given to studies conducted in Scotland) and its direct relevance to reducing reoffending). Following this process, an additional 57 texts were included in the review at this stage.

It is hoped that this second version of the Reducing Reoffending Evidence Review will remain a work in progress that will be updated as additional evidence becomes available. The paper was subject to peer review from analytical and policy officials in the Scottish Government, academics and other experts whose contributions greatly enhanced its quality.

In addition to this review, the Scottish Government has recently published a review of What Works to Reduce Crime[62]. The What Works to Reduce Crime review takes a broader perspective, considering ways in which the underlying causes of crime, deterrence and reducing opportunities to offend can reduce crime. There is necessarily an overlap between these topics, and where appropriate readers will be recommended to seek further information in the What Works to Reduce Crime review.


Due to research constraints, in the vast majority of cases it is not possible to know whether the effect of reduced reoffending was directly caused by a particular intervention. The above review of the evidence shows that some criminal justice interventions are associated with reductions in reoffending. This temporal association should not, however, be misinterpreted as causality: in the vast majority of cases, it is not possible to say whether the effect of reduced reoffending was directly caused by a particular intervention. The primary reason for this is that most evaluations of criminal justice interventions, especially in Europe, use, in the best of cases, vaguely defined or loosely comparable comparison groups, and in the worst, no comparison group at all. This lack of robust comparison group designs substantially weakens the internal validity of evaluation findings (i.e. the extent to which we can infer the effect was caused by the intervention), and raises the possibility that change is the product of selection effects: offenders participating in programmes are likely to differ in important ways from non-participants, for example they might be more motivated to change, and these unique characteristics, rather than the intervention, may have made them less likely to reoffend in the first place[63].

The timescales for completing this piece of work were tight and precluded a fully comprehensive search of the literature. As such the review does not claim to provide an all-inclusive overview of research into what works to reduce reoffending as there are likely to be gaps in the literature covered in this review.

It is also important to note that this review does not claim to provide a "gold-standard" solution to the problem of reoffending that can successfully fit all offenders, as desistance from offending is a complex, subjective process and what may work for some may not work for others. However, it is hoped that the review will provide some direction to policy makers on the type of interventions that have, overall, proven more effective in reducing reoffending.

Figure One: A summary of desired intermediate outcomes of reducing reoffending programmes based on criminogenic needs (adapted from Bisset (2015)[64])

Figure One: A summary of desired intermediate outcomes of reducing reoffending programmes based on criminogenic needs


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