This article presents an in-depth evaluation of a specialized reintegration initiative within the Dutch Probation Service focused on individuals convicted or suspected of involvement in terrorism. Using 72 interviews with program staff as well as several of their clients, the authors assess the initiative’s program theory, its day-to-day implementation and provide a qualified assessment of its overall effectiveness in the 2016 to 2018 period. The results suggest that the initiative is based on a sound understanding of how and why individuals may deradicalize or disengage from terrorism behaviorally, but that it continues to face serious challenges in terms of accurately defining success and systematically gathering objective indicators of i...