Dans un contexte d'instabilité des organisations partisanes et une performance électorale en déclin, cette thèse cherche à expliquer comment et pourquoi l'UCR a survécu dans le système politique argentin. La réponse présentée tente de compléter une explication de caractère agentiel et l'autre de caractère structurel. L'UCR a réussi à survivre en fournissant à leurs dirigeants des ressources tant organisationnelles qu'institutionnelles, selon lesquelles les radicaux développent alternativement de nombreuses stratégies (par rapport à l'électorat et à leurs pairs). Ceci se déroule dans le cadre d'une organisation territoriale à plusieurs niveaux qui permet d'une part la coexistence de ces stratégies et d'autre part, qui rassemble et favorise la formation de coalitions nationales pour concourir aux élections présidentielles et être ainsi plus compétitifs. L'argument se déroule en sept chapitres. L'introduction fait une revue de littérature, présente l'argument et méthodologie. Le deuxième chapitre décrit le cadre institutionnel et ses effets; le troisième retrace la construction de liens avec la société, le quatrième caractérise les leaders, leurs espaces sociaux, intérêts et considérations et présente également les ressources disponibles et les stratégies développées à cet égard qui seront décrites plus détaillée dans les deux chapitres suivants. Le dernier chapitre démontre, à partir de l'analyse des trois dirigeants, leurs ressources, carrières et stratégies, la façon dont tous les éléments sont mis en jeu et interagissent, prenant en compte leur survie. Enfin, certaines conclusions sont présentées dans le but d'élargir et généraliser les idées au-delà de l'étude de cas. / In a context of instability and breakdowns of party organizations in Latin America and given the decline in its performance in national elections in recent decades, coupled with the importance of knowing the inner functioning of political parties, this dissertation seeks to explain how and why the Unión Cívica Radical (UCR) has survived in the past 30 years, and how and why it has continued competing over time for the various representative positions in the Argentine political system. The tentative answer presented here complements an explanation of an agential character with a more structural one. The UCR bas managed to survive as a national organization because it provides its leaders with organizational and institutional resources which Radicals alternately consider in order to develop different strategies (towards constituents and their colleagues) within the framework of a multilevel structure that facilitates the coexistence of even contradictory strategies and alliances. At the same time, this brings the party together over expectations of forming a national government, promoting the development of national interests, lines and coalitions to compete for the presidency. It combines an agential type response (considering various strategies according to available resources that contribute to the survival of Radical leaders) with a more structural one, concerning the resources available to the party leaders and how the effects of the federal multilevel organization facilitate organizational survival. Radical leaders have at their disposal institutional resources -which derive from the control of the state apparatus, allowing them to distribute private goods and develop strategies of patronage and pragmatic alliances; additionally, they possess organizational resources -as a territorially extended bureaucratic structure, a political program and ferrous linkages to external organizations. They predominantly use one or the other depending on their availability, which mainly derives from whether or not they hold the administration, acting alternately as government or partisan leaders. In this sense, what differentiates the UCR from other national party organizations in the country is that whether or not it is electorally successful, it survives and not only at the provincial and/or municipal level, but also nationally. Even outside the government, Radicals are committed to the survival of the party, especially given its Radical political socialization and identity. At the same time, the organizational structure and resources of the university -both of national and federal in character- keeps them not only committed but also interested in keeping things this way. Considering other national parties, the Partido Justicialista does not have the bureaucratic structure and the relation that Radicalism bas with the university, while the Partido Socialista lacks the experience of exercising national government power. Finally, it can be added that in the case of provincial ruling parties, their influence does not exceed their districts' boundaries.