The Early Intervention Foundation has been working with the Home Office to produce reports with the aim of helping local areas make more informed decisions about (i) how best to identify those children and young people who may be at risk of involvement in gangs or youth violence, and (ii) what types of programmes or interventions appear to work or not to work in preventing involvement in gangs and youth violence.
The first report is a review of risk and protective factors based on academic studies which followed individuals, often from early childhood and collected data on risk variables at regular intervals to identify which ones correlate most strongly with later outcomes.
The second report looks at the features associated with effective and ineffective interventions in delivered in the UK and abroad and examines what the evidence tells us about how best to respond to these risks.
See http://www.eif.org.uk/publication/preventing-gang-and-youth-violence/