Evaluation of incentivised substance free living wings in prisons
A process and impact evaluation in 4 prisons, which uses a waitlist randomised controlled trial, Bayesian survival analysis, and qualitative analysis.
Applies to England and Wales
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Incentivised Substance Free Living wings (ISFLs) are dedicated areas within prisons designed to support prisoners who want to live drug-free. These wings provide a structured, calm environment where residents agree to a behavioural compact, take part in regular drug testing, and receive incentives such as more time out of cell or access to additional equipment and activities. ISFLs aim to create safer, more stable spaces that help prisoners focus on recovery, build positive relationships, and develop skills that support healthier choices.
As part of the Tackling Drug Misuse in Prisons evaluation programme, funded by the Cabinet Offices’ Evaluation Accelerator Fund, two complementary studies were carried out to understand how ISFL wings work and what difference they may make.
The first study was a process evaluation, which explored how ISFLs were being delivered in three prisons. Using interviews, focus groups, and observations, researchers gathered the views and experiences of staff and prisoners to understand how the wings were operating in practice, what was helping to create a safe and supportive environment, and what could be improved.
The second study was an impact evaluation, which used a waitlist randomised controlled trial across 4 prisons to examine whether ISFLs support a more stable prison environment. Prisoners on waiting lists for ISFL places were randomly allocated either to move to the ISFL sooner or to remain on a standard wing for at least three months. The study then compared the 2 groups using routinely collected prison data on incidents such as assaults, self-harm, and disorder, providing robust evidence on the impact of ISFLs on prison stability.