This chapter focuses on research designed to evaluate the de-radicalisation/rehabilitation programs administered to the detainees. The detention of members of terrorist organisations is a fact of life, an inevitable part and parcel of the war on terror. In recent years, the possibility of using the incarceration situation to effect de-radicalisation of detained terrorism suspects has been exploited in several programs carried out in Muslim nations, or countries with significant Muslim populations. These programs aimed to persuade detainees, members of extremist Islamic organisations, that violence against unarmed civilians is contrary to the teachings of Islam, and is explicitly prohibited by the Quran. The Sri Lankan rehabilitation program contained a number of ingredients that are highly consistent with the psychological analysis of detainee's states. The Liberation Tigers of Tamil Eelam (LTTE) has been known as one of the most vicious and ruthless terrorist organisations ever.