Challenges to scaling a youth violence reduction intervention: Evidence from a field experiment and qualitative data

Concerns around the exposure of young people to violence lie at the top of the UK policy agenda. We evaluate a flagship violence-reduction intervention in London, known as Your Choice, that targets adolescents at risk of exposure to violent crime. The intervention trains youth practitioners in CBT, who deliver these techniques to adolescents over 12-18 weeks. Delivery is embedded within pre-existing services that London Local Authorities are statutorily required to provide, so accounting for constraints to scale-up from the outset. Many challenges to retaining voltage at-scale relate to system-wide factors that are hard to measure quantitatively. We therefore combine qualitative and quantitative evidence to understand intervention impacts moving from an internal pilot to a full scale efficacy trial. While the pilot showed the promise of Your Choice, the intervention faced challenges to scale. We document four reasons for this: (i) initial pilot participants differ from those recruited at scale-up; (ii) uncertainty over future funding and staff turnover; (iii) binding workload capacity constraints for practitioners; (iv) a rise in per participant intervention costs. We derive implications for future evaluations of similar interventions in public services that operate near full capacity, to help build the evidence base on how to overcome these fundamental sources of voltage drops.