Em 1905, o V Congresso da Federa??o Oper?ria Regional Argentina (FORA) aprovou uma resolu??o que recomendava a todos os seus aderentes a propaganda dos princ?pios econ?micos e filos?ficos do comunismo an?rquico. A identifica??o da maior institui??o sindical da Argentina com a ideologia anarquista n?o s? demonstrava a for?a do anarquismo no movimento oper?rio como tamb?m foi um fato que encontrou poucos precedentes na hist?ria do movimento libert?rio. Longe de apenas seguir os exemplos de seus pares europeus, os anarquistas argentinos desenvolveram concep??es originais e que fundamentaram suas pr?ticas no movimento oper?rio. A presente disserta??o pretende analisar as concep??es e pr?ticas sindicais dos anarquistas argentinos entre 1905 e 1915, per?odo em que a FORA esteve abertamente identificada com o anarquismo. Buscamos compreender as formula??es anarquistas sobre a a??o, organiza??o e finalidade do sindicalismo; suas pr?ticas concretas frente a quest?es como a solidariedade de classe, a luta por melhores condi??es de vida para a classe trabalhadora, o enfrentamento contra o Estado e o internacionalismo; e suas rela??es com o sindicalismo revolucion?rio, corrente pol?tica que disputava a dire??o do movimento oper?rio argentino e compartilhava certos princ?pios com o anarquismo, como o antiparlamentarismo e a defesa da a??o direta e da greve geral. In 1905, the 5th Congress of the Argentine Regional Workers? Federation (Federaci?n Obrera Regional Argentina, FORA) approved a resolution which advised to all its members the study and propaganda of the economical and philosophical principles of anarchocommunism. Being the major labor federation in Argentina, its identification with anarchist ideology not only shows how anarchism was strong among the labor movement, but also stands as a fact with little to no precedence in libertarian movement history. Far from following the steps of fellow European counterparts, anarchists in Argentina developed original concepts as a foundation for their practices in the labor movement. This dissertation aims to analyze anarchist concepts and practices in the Argentine labor movement between 1905 and 1915, a period in which the FORA openly identified itself with anarchism. We sought to understand anarchist purposes for labor action, organization and its aims; their concrete practices regarding issues such as class solidarity, struggles for better life conditions for the working classes, clashes with the State and internationalism; and its relationships with revolutionary syndicalism, a political current disputing control of the Argentine labor movement which shared some principles with anarchism, such as anti-parliamentarism and support for direct action and general strikes. Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq