During the first three decades of the twentieth century, leftist thought in Cuba favoured anarcho-syndicalism more than any other ideology. Moreover, its practicality made it a popular choice among workers, who, attracted by the prospect of immediate and obtainable benefits, such as higher pay and fewer working hours, could help to prepare for the more distant revolution. This blend appealed to factory workers in Havana, in particular, and it is on that group that this thesis concentrates. A substantial growth in manufacturing industry in Cuba's capital during the 1910s facilitated in the creation, and then in the expansion, of a union to support the growing factory workforce. This thesis traces the lifespan of the Sindicato General Obrero de la Industria Fabril (Manufacturing Union Workers' General Union - SGOIF) and of its periodical El Progreso (Progress). Precursors to the SGOIF are studied and, for the first time, the union and its mouthpiece are analysed in detail. To achieve an in-depth knowledge of the SGOIF, it has been necessary to explore the structure of the union, who belonged to it, what tactics it used and what its ideology was. In this respect, both the philosophy behind the SGOIF and how this was employed in the real world have been examined. In order to fill the void left by Cuban social historiography, periodicals and government records are among the primary sources that have been inspected, an undertaking that has provided a wealth of information about the need for industrial unionism in Cuba and the perceived importance of direct action tactics among workers during the 1910s and 1920s. Through such examination, it has become clear that workers of the period possessed class-consciousness prior to the foundation of a communist party in Cuba. This thesis shows why anarchosyndicalism in Cuba collapsed (detailing the part that the SGOIF played in its downfall), paving the way for communism, an ideology still so important in the political and social fabric of Cuba in the twenty first century.