Buenos Aires is Argentina’s wealthiest, largest, and most populous province, and has long been the key prize in all major electoral struggles, has received little scholarly attention. This first account of its political history between 1912 and 1943 underscores its role as a vital factor in national political life. Particular attention is given to the part the province has played in national presidential elections, the relationship between provincial administrations and the national government, and the struggle between the two principal political parties, the Partido Conservador and the Union Civica Radical, which vied for control of the province during the early part of this century. Based on a wide range of sources, including newspapers, government documents, archival sources, and personal interviews, the book describes the fascinating political interplay of competing forces in the most important electoral arena of one of Latin America’s most important countries.