This is the first compilation of primary sources that document the history and tradition of liberal thought in Argentina throughout the nineteenth and first half of the twentieth century. With only two exceptions, none of the works have ever been translated into English until now. Liberal ideas were very important in Argentina from the time of independence. The Argentine constitution (1853-60), in force for a long time, was based on liberal principles taken from both the North American and the European tradition. The general structure of the collection is chronological, taking the reader through an analysis of different periods of liberal thought in Argentina: from liberalism as opposed to dictatorial rule, to liberalism as the framework of the National Constitution (1852-60). Importance is given to the development of liberalism in government and opposition (1857-1910) and to the last period (1912-40), the twilight of liberalism. Chapter 1 addresses the dictatorship of Juan Manuel de Rosas (1837-50), during which time a set of liberal ideas was formed that would subsequently have a decisive influence on the second period, the formation of the National Constitution (1852-60). Chapters 3 and 4 consist of writings that chronicle the surge of liberalism in Argentina, first, during the period between 1857 and 1879, and, later, between 1880 and 1910. These chapters reflect the great political, economic, and social debates that exemplify the variety and richness of the body of liberal ideas during this time. The writings in the final chapter review the gradual decline of liberalism. They rescue from obscurity those voices and writings that upheld and defended liberal ideals in several aspects, namely, those ideals concerning electoral and constitutional reforms and the resistance of the advance of different expressions of totalitarian dictatorship during the twentieth century.