In parts of sub-Saharan Africa, radical Islamists are targeting fragile and conflict-affected states and encouraging the formation of groups which act against the state (either violently or subversively). These processes exacerbate existing fragility and increase conflicts among communities in countries that already suffer from poor social cohesion and integration. This paper describes the ideas and methods with which radical Islamist groups are destabilising some fragile and conflict-affected states in sub-Saharan Africa, such as Sudan, Nigeria and Chad. It also evaluates the extent to which modern communication technologies help spread these ideas among Islamists in these states. In supporting fragile and conflict-affected states that are being infiltrated by radical Islamism, international donors should tackle two related phenomena: 1) regulating the telecommunication market and use of the Internet and social media; and 2) improving education. The non-violent aspects of Islamist radicalisation processes suggest that a dialogue with radical Islamists is still possible. In this sense, some of their projects, particularly their efforts at Arabisation, could be harnessed to increase literacy levels in order to favour general education and development and diminish fragility.