This chapter traces the ideological genesis of the notion of ‘propaganda by the deed’, recounts the terrorist wave which it partly inspired in the 1880s–1920s and highlights the contemporary legacies of the concept and its terrorist ramifications. The elaboration of propaganda by the deed as an activist strategy in the last years of the First International is charted, as well as subsequent, narrower reinterpretations of propaganda by the deed focusing on violence as the means to achieve political goals. The four-decade anarchist terrorist wave and its complex links with propaganda by the deed are then examined, highlighting tensions between the systematic characterisation of anarchism as a terrorist movement and actual internal divisions re...