The article analyses cooperation between the state and the autonomous communities in Spain, as well as between the communities themselves. First, it outlines the general characteristics of the Spanish autonomous state before focusing on a rather atypical phenomenon: the territorial structure has not been integrated into the Constitution; rather, it has developed based on the procedures established in the Constitution itself. This gives the Spanish Constitution a procedural configuration that complicates the establishment of cooperation mechanisms between the State and the Autonomous Communities that are not present directly as such in the constitutional text. Subsequently, the distinct forms of cooperation are analysed: the mechanisms for integrating autonomous will into state decision-making process; vertical cooperation mechanisms between the state and autonomous communities; horizontal cooperation mechanisms between autonomous communities; bilateral cooperation relations between the state and each autonomous community; the autonomous communities’ participation in designating state bodies; and ultimately, their participation in European decision-making processes. Structures that were not foreseen in the Constitution have been developed at all levels and in all areas of cooperation to overcome the specific deficiencies of the procedural configuration of the constitutional text in territorial matters. Overall, it can be concluded that these structures function adequately, although some of them have specific deficiencies which, to a greater or lesser extent, manifest opposite phenomena. Firstly, there is tension between an asymmetric model of the autonomous state, which is defended by peripheral nationalist parties, and an egalitarian model. Secondly, there is an absence of an autonomous political culture among national parties at state level, which tend to use their position in autonomous governments to oppose the state government instead of defending the interests of their autonomous communities.