As stated by an earlier RAN policy paper, multi-agency structures and working processes are crucial for early and effective identification of individuals at-risk, improved information-sharing, joint decision-making, and coordinated action. Multi-Agency Working (MAW) breaks down historical silos between agencies and leads in different cities to cooperation, instead of fragmentation of services. Although practitioners and academics endorse the added value of MAW, they also pinpoint some prerequisites of building an effective collaboration (building trust, awareness, ethical and legislative guidance, etc.). Two main challenges for MAW have been indicated, namely (1) the lack of established policies and procedures for MAW in countering violent extremism and thorough evaluation research of the MAW approach and (2) the barriers of information sharing. In this presentation, we will focus on a process-evaluation methodology of MAW within the three countries (Belgium, the Netherlands, Germany) to identify the effective key components of an intervention and thus help to understand why a program or intervention was successful or not.