By Lorraine Mazerolle,Adrian Cherney,Elizabeth Eggins,Lorelei Hine and Angela Higginson

Multiagency responses to reduce radicalisation often involve colla-borations between police, government, nongovernment, business and/or community organisations. The complexities of radicalisation suggest it is impossible for any single agency to address the problem alone. Police‐involved multiagency partner-ships may disrupt pathways from radicalisation to violence by addressing multiple risk factors in a coordinated manner.Objectives:1. Synthesise evidence on the effectiveness of police‐involved multiagency interventions on radicalisation or multiagency collaboration. Qualitatively synthesise information abouthowthe intervention works (me-chanisms), interventioncontext(moderators), implementation factors and eco-nomic considerations.Search Methods:Terrorism‐related terms were used to search the Global PolicingDatabase, terrorism/counterterrorism websites and repositories, and relevantjournals for published and unpublished evaluations conducted 2002–2018. Thesearch was conducted November 2019. Expert consultation, reference harvestingand forward citation searching was conducted November 2020.Selection Criteria:Eligible studies needed to report an intervention where policepartnered with at least one other agency and explicitly aimed to address terrorism,violent extremism or radicalisation. Objective 1 eligible outcomes included violentextremism, radicalisation and/or terrorism, and multiagency collaboration. Only impact evaluations using experimental or robust quasi‐experimental designs were eligible. Objective 2 placed no limits on outcomes. Studies needed to report anempirical assessment of an eligible intervention and provide data on mechanisms,moderators, implementation or economic considerations.Data Collection and Analysis:The search identified 7384 records. Systematic screening-identified 181 studies, of which five were eligible for Objective 1 and 26 for Objective 2.

Oslo, Norway: Campbell Collaborative, 2021. 88p.