There is continued investment and attention being paid to programs of disengagement and deradicalization (D&D) for Islamist terrorists. Whilst there is some evidence of positive effects of different programs, it is widely acknowledged that rehabilitative efforts with terrorists are in their infancy and that there is a great deal of potential for learning, development and refinement. The present article examines rehabilitation programs for Islamist militants in light of the literature on rehabilitative interventions for “ordinary” criminal offenders, which have been in development now for more than 50 years. Principles of best practice as well as challenges in the field of criminal corrections are outlined, and the extent to which these may be applicable in the context of dealing with terrorists is discussed. Although the content of criminal and terrorist rehabilitation programs will always differ, criminology can help to clarify issues, improve practice, and develop realistic expectations for rehabilitation of Islamist terrorists.