The paper analyzes the spanish constitutional framework, the provisions of the spanish «Estatutos de Autonomía» (legal instruments of each spanish autonomous community’s self government), the conventional activity and the constitutional jurisprudence on the respective position of the spanish State and autonomous communities in the so-called "ascending stage” (or the participation of both national and regional levels of government in the enactment of the European Union’s legislation), as well as in the known as the «descending stage» (or the distribution of powers between the State and the autonomous communities for the national implementation of European Union’s legislations and decisions).El artículo analiza la normativa constitucional y estatutaria, la actividad convencional y la jurisprudencia constitucional sobre la respectiva posición de Estado y comunidades autónomas, tanto en la denominada «fase ascendente» o de elaboración de las normas y decisiones de la Unión Europea como en la conocida como «fase descendente» o de ejecución interna de esas mismas normas y decisiones
