For decades, the constitutional theory has among its most important problems the issue of the effectiveness of its rules. Although it is an issue that affects, in general, all constitutional norms, the problem becomes more acute in the case of social rights. The following pages offer an explanation of the difficulties we face when trying to make constitutional norms effective based on a historical and conceptual reading of social rights and of the State model that can make them a reality: the social State.For decades, the constitutional theory has among its most important problems the issue of the effectiveness of its rules. Although it is an issue that affects, in general, all constitutional norms, the problem becomes more acute in the case of social rights. The following pages offer an explanation of the difficulties we face when trying to make constitutional norms effective based on a historical and conceptual reading of social rights and of the State model that can make them a reality: the social State.Desde hace décadas, la teoría constitucional tiene entre sus problemas más importantes el tema de la eficacia de sus normas. Aunque se trata de una cuestión que afecta, en general, a todas las normas constitucionales, el problema se hace más agudo tratándose de los derechos sociales. En las páginas que siguen se ofrece una explicación de las dificultades que enfrentamos al intentar hacer eficaces las normas constitucionales a partir de una lectura histórica y conceptual de los derechos sociales y del modelo de Estado que los puede hacer realidad: el Estado social.