The model for assessment for concerns about extremism (MACE) is a process-model developed for a multi-agency collaboration where relevant authorities assess concerns about extremism in a Danish context. This assessment is made with the sole purpose of early prevention. The concerns can range from mild to very serious concerns where there is need for some kind of preventive measure or intervention. This chapter introduces the development of the model as well as a description of the phases of the model and the assessment tools that support that process. Finally, a range of learning points and recommendations are listed to sum up the chapter.