This article examines how group representations can be used strategically to induce social change. The speeches delivered by Patrice Lumumba during the decolonization of the Belgian Congo were analysed using the content analysis software ALCESTE. Lumumba used radically different descriptions of Belgians and Congolese depending on the period during which the speech was delivered and on the audience he was addressing (Congolese or Belgian). When addressing Belgians, he described their countrymen as benevolent allies who could assist the development of Congo, and the Congolese as pacific and friendly When addressing Congolese audiences, Belgians were described as oppressors, and Congolese as victims. In addition he emphasized the unity of the country more at the end of the decolonization process than at its onset. Considering that his nationalist and pan-African aims remained stable, we suggest that this variability stems from the different actions expected from his audiences, as a function of their group membership and the political context. We argue that this performative dimension cannot be captured if group representations, including stereotypes, are only viewed in cognitive terms. In addition, we show that they should be studied not only as justifications for the existing social order but also as instruments of social change.