This thesis is a comparative analysis of the propaganda programmes employed in the motivation of volunteer soldiers in the Spanish Civil War, 1936-1939. It focuses on the successes and failures of each programme in convincing volunteers from various political backgrounds to fight for values that differed from those for which they took up arms. The programme of the Francoist National Army, known as 'the Crusade', presented the war as a conflict between the true, Christian Spain and a Muscovite invader, intent of destroying the nation and enslaving its people. The Popular Army's programme was neither as singular nor as emotive and the message that was presented was a diffuse one. Evoking Spanish nationalism, proletarianism and antifascism, 'Republicanism', as this thesis shall refer to it, was designed to broadly appeal to all groups within the disparate Republic polity. The thesis first establishes the content of both programmes clearly and the means by which they were disseminated, with special attention paid to the Political Commissariat of the Popular Army. Attention then turns to how each programme was presented to the volunteer soldiers of four distinct political affiliations across four case study chapters. On the Republican side the case studies chosen are those of the anarchist Confederación Nacional del Trabajo and the Basque nationalist Partido Nacionalista Vasco, while the Francoist case studies are the fascist Falange Española de las JONS and the reactionary, parochial and Catholic Comunión Tradicionalista. Each case study examines how each programme was presented to politically motivated soldiers and what ideological questions were emphasised, answered, altered or ignored in order to ensure volunteers' continued bellicosity. The thesis will highlight the innate advantages of having a coherent, singular motivational programme such as the Crusade over a more diffuse, all-encompassing programme, such as the one presented to the soldiery of the Popular Army. However, it will also highlight that, with a propaganda service as dedicated as the Republic's Political Commissariat, the Republic was able to overcome some (although not all) of its inherent disadvantages.