Boston Ceasefire — Group Violence Intervention

Summary

The Boston Ceasefire experiment is the foundational study in focused deterrence — a violence reduction strategy that combines a credible enforcement threat with social service outreach, delivered directly to the individuals most likely to commit or be victims of violence. The 63% reduction in youth homicides in 24 months was unprecedented in a city the size of Boston. The mechanism differs fundamentally from conventional policing: rather than targeting locations, it targets people — specifically, a small network of gang-involved individuals responsible for a disproportionate share of violence — and communicates directly with them. The approach has been replicated in more cities than almost any other violence reduction strategy, with consistent large effects. It is notable as one of the few public safety strategies with both strong causal evidence and substantial community buy-in from the social service component.

Research question

"Can a focused deterrence strategy — directly communicating consequences to the highest-risk individuals while offering social services — reduce gang-related youth homicide?"

Methodology

Result

Positive

Youth homicides: −63% in 24 months (from 3.8 to 1.4 per 100,000); gun assault incidents: −25%; effect attributable to intervention not broader national trend through synthetic control analysis

Evidence strength

Limited

Observational or pre-post design; correlation not necessarily causal.

Replication status

Replicated