Founded in 1891, the Union Civica Radical, generally known as the Radical Party, is the oldest national political party in Argentina. As the strongest opposition party during the 1890s, a pivotal decade in the birth of Argentina’s party system, the Radical Party effected a critical development in Argentine politics: it created a system of open confrontation and political competition. This study offers not merely a revised version of the party’s story but also a new perspective on the politics of the nation as a whole.