In recent years, the number of counter-radicalization and deradicalization programs has steadily increased, and they belong now to the standard counterterrorism and conflict resolution repertoire of many countries. How is the personnel of these programs trained to perform its duties and what does this tell about the relationship between academic and practitioner understandings of countering radicalization and deradicalization? This article aims at answering these questions by comparing the state of the art in evidence-based radicalization and deradicalization research with a detailed analysis of primary data concerning twelve training courses for personnel in this field. It finds that training courses are significantly disconnected from research. On the other hand, training in this field indicates that the academic literature is not well-grounded in the practical realities of delivering interventions. Both findings reveal the need for a more mutually beneficial relationship that can help improve practitioner training and making (de)radicalization research more practitioner-oriented.