In the early part of the twentieth century, Argentina's Socialist Party became the largest and most effective socialist organization in Latin America. Richard J. Walter's interpretive study begins with the party's origins in the 1890s, traces its development through 1912, and then offers a comprehensive analysis of its activities and programs during the almost two decades of civilian, democratic government that ended with the military coup of 1930. His aim has been to provide a detailed case study of a Latin American political party within a specific historical context. The work gives particular attention to the nature of party leadership, internal party organization, attempts to win the support of the Argentine working class, party activities in national elections and the National Congress, and internal disputes and divisions. In discussing these topics, Walter draws heavily on government documents, including national and municipal censuses, ministerial reports, and the Argentine Congressional Record. He also makes extensive use of national and party newspapers and journals, political memoirs, and collections of essays by party leaders. Walter concludes that the party enjoyed relative electoral and legislative success because of efficient organization, capable leadership, and specific, well-reasoned programs. On the other hand, it failed to create a firm working-class base or to extend its influence much beyond Buenos Aires, mainly because of its inability to relate adequately to the needs of the proletariat and to the growth of nationalist sentiment. The analysis of these successes and failures also provides an important background for understanding the rise to power of Juan Perón and Peronism.