The book studies the social, religious and political impact of these reform movements in both historical and contemporary times and asks why some have become successful as popular mass movements, while others failed to attract substantial audiences. It also considers jihad-minded movements in contemporary Mali, northern Nigeria and Somalia and looks at modes of transnational entanglement of movements of reform. Against the background of a general inquiry into what constitutes 'reform', the text responds to the question of what 'reform' actually means for Muslims in contemporary Africa.