For years, former right-wing extremists have been successfully involved in disengagement and deradicalization, whereas in the field of Islamist extremism, former extremists have hardly been involved in exit processes. This article shows that formers are more successful than other actors in establishing trust with the target person. Involving former extremists in deradicalization work can also be of great value to them and positively influence their own rehabilitation and reintegration process. Yet this effort faces challenges, which are discussed in this article. So far, there are only a few former Islamists in Germany and Europe who are eligible for this work. However, as the example of Germany demonstrates, it is possible to include formers from other geographical contexts. This is shown in the case of a prevention project in Germany that includes former fighters from Lebanon. Because of their comparable life experiences in the respective war and conflict contexts, formers can better understand the experiences of the target group. Thus, former extremists can be involved as mentors and become a complementary part of already existing practices and structures. In this context, integration into existing structures is desirable. This article discusses the prerequisites, challenges and advantages of engaging formers in deradicalization work.