The Spanish institutions of the Ancien Régime were the superstructure that, with some innovations, but above all through the adaptation and transformation of the political, social and economic institutions and practices pre-existing in the different Christian kingdoms of the Iberian Peninsula in the Late Middle Ages, presided over the historical period that broadly coincides with the Modern Age: from the Catholic Monarchs to the Liberal Revolution (from the last third of the 15th century to the first third of the 18th century) and which was characterized by the features of the Ancien Régime in Western Europe: a strong monarchy (authoritarian or absolute), an estamental society and an economy in transition from feudalism to capitalism.

The characteristics of the Ancien Régime are dispersion, multiplicity and even institutional collision, which makes the study of the history of institutions very complex. The very existence of the institutional unity of Spain is a problematic issue. In this historical period there were unitary institutions: notably, and transcendental in the external perception of the Hispanic Monarchy, the person of the king and his military power; inwardly, the Inquisition. Others were common, such as those inherent to the estamental society: nobility, clergy and corporations of very different types were organized in a way that was not very different in each kingdom. A Catalan Cistercian monastery (Poblet) was interchangeable with a Castilian one (Santa María de Huerta); a Mesteño rancher, with another of the House of Zaragoza; the aristocracy merged into a network of family alliances. But others were markedly different: the Cortes or the Treasury in the kingdoms of the Crown of Aragon had nothing to do with those of Castile and León. Even with the imposition of Bourbon absolutism, which reduced these differences, the Basque provinces and Navarre maintained their fueros. The State and the nation were being forged, largely as a consequence of how the institutions responded to the economic and social dynamics, but they would not present themselves in their contemporary aspect until the end of the Ancien Régime.

Society in Ancient Régime Spain The sociedad de la España moderna ("society of modern Spain" in the sense of the Modern Age or Ancien Régime) was a network of communities of diverse nature, to which individuals were attached by bonds of belonging: territorial communities in the style of the house or the village; intermediate communities such as the manor and the cities and their land (alfoz or comunidad de villa y tierra, of very different extension); political communities or broad jurisdictions such as the provinces, the adelantados, the veguerías, the intendancies or the kingdoms and crowns; professional communities such as corporations, fishermen's confraternities, or the universities; religious communities; etc.

The kingdom was contemplated with an organicist analogy, as a body headed by the king, with his supremacy, with the different communities and orders that formed it as organs, articulations and limbs. Men and women were linked by personal ties, such as family and kinship ties. Each bond was governed by common rules that were to govern its functioning and experience. In the Ancien Régime, communities were hierarchical, every body had its authority, and there were links of integration and subordination. But each link had an ambivalent value, of domination and paternalism: they had to guarantee the survival of individuals while maintaining social relations of subordination. What in the contemporary world are understood as public functions, were in the hands of private individuals, whether they were houses, lordships or domains of the king, with one territory having total autonomy from another. The very concept of private was meaningless, since there was no effective differentiation between public and private in the pre-state or pre-industrial society.

The nobility and the clergy were the privileged estates. From the 16th century onwards, the nobility tended to become more courtly and moved to Madrid, in the vicinity of the Court. The clergy was a more open estate, since individuals could join without regard to their social status, although it was also a hierarchical group with different degrees within its structure. The common state was the most heterogeneous and numerous. It ranged from the poorest peasants to the incipient bourgeoisie (the bourgeoisie of the intelligentsia: mostly literate people with administrative positions; and the bourgeoisie of business). The degree of integration of various persecuted minorities (Judeo-converts, moriscos or gypsies) underwent different alternatives.

Monarchy, nobility and territory

The apex of the institutional system was the monarchy, justified from the beginning of the reconquista as an inheritance of the Visigothic Hispania in the Cantabrian nuclei: kingdom of Asturias, kingdom of León and county and later kingdom of Castilla; or of the Carolingian feudalism in the Pyrenees: Condal Court of Barcelona, later principality of Catalonia, county and later kingdom of Aragon, and kingdom of Navarra. This, in fact, had united almost all the peninsular Christian territories at the beginning of the 11th century, to later disintegrate them with the inheritance of Sancho III The Great among his descendants of the Jiménez dynasty, who were at odds with each other as they expanded territorially throughout Al-Andalus. By then the concept of hereditary monarchy was already sufficiently established to use it as a patrimonial institution, within the vassal dynamic of feudalism, with all the limitations that this expression has in the Iberian Peninsula. The European influence that arrived with the Camino de Santiago and the Order of Cluny determined that it was the House of Burgundy that would end up being linked to the western kingdoms (Portugal, León and Castile). The same justifying procedures (to which the very existence

of the monarchy was added) were used to justify the social predominance of the nobility (the bellatores or feudal defenders), who with the high clergy formed a single ruling class: the privileged.

The formation of the authoritarian monarchy culminated with the powerful Trastámara dynasty, originated in Castile in the person of a bastard, Henry II of Castile, raised to power by the high nobility who were zealous to avoid the same concentration of power, which would also be implanted in Aragon as a consequence of the Compromise of Caspe. The crisis of the 14th century had been decisive in producing a clear separation between the high and low nobility of hidalgos and knights, whose social prestige, when it could not be sustained by the control of lands, was sought with all kinds of probanzas, habits, ejecutorías, kings of arms, coats of arms ... which, if they could not be supported with those, did not hide their economic decadence. Geographically, there was also a gap between the north of the peninsula -the Cantabrian and Pyrenean mountains where the original lands of the noble houses were sought, but where there were no large domains and the greater equality of conditions allowed the myth of universal nobility to be born- and the south -dominated by the encomiendas of the military orders and the great noble estates-. For the non-privileged, there remained the perception of pride as an Old Christian, which was legally expressed in the statutes of limpieza de sangre, which were extended to all types of institutions after the anti-conversion revolt of Pedro Sarmiento in Toledo (1449). This legal discrimination was maintained as a decisive factor of social cohesion even more so after the expulsion of the Jews (1492) and the Moriscos (1609), maintaining as a useful scapegoat the existence of the New Christian, a condition from which neither the highest noble houses nor the king himself escaped (Libro Verde de Aragón, Tizón de la Nobleza).The author of the second was Cardinal Francisco de Mendoza y Bovadilla,  written in 1560 as a memorial to King Philip II, where he questioned the cleanliness of blood of the Spanish nobility. The Libro verde de Aragón, from the first half of the 16th century, was a similar manuscript by a counselor of the Aragonese Inquisition, which was widely disseminated.

The territorial union of the Catholic Monarchs (by marriage: Aragon and Castile, or conquest: Canary Islands, Granada, Navarre, America, Naples, North Africa), was followed by the addition of vast territories in Europe with the arrival of the Habsburg dynasty, whose conception of power was based on respect for local peculiarities (not without conflicts, such as the Revolts of the Comuneros and the Brotherhoods with Charles V or the crisis of 1640 with Philip IV). The unitary conception of the peninsular domains allows historiography to speak of Hispanic Monarchy, despite the fact that the union is in the person of the kings and not in the kingdoms, which maintain their laws, languages, currencies and institutions. The attempt to unify them from the union of the noble families, especially in the foundation of the concept of Grandee (1520), which incorporated a small number of aristocratic houses of the two crowns (with clear Castilian predominance). Marriage alliances were encouraged, with the manifest aim that the social elite in practice was the same in all of them. The union with Portugal, which lasted sixty years (1580–1640), was also attempted to consolidate in the same way (not without misgivings; hence the Portuguese saying about Spain: "neither good wind nor good marriage").

Finally, the Bourbon dynasty (curiously, of Navarrese origin) will impose the French customs of absolute monarchy, not only in court protocol, but also in the centralist configuration of the State and in the succession provisions of the Salic law, after a civil war with a European dimension: the War of the Spanish Succession.

The territorial conformation of the Hispanic Monarchy in such a wide range of territories allows us to speak separately of the American institutions, those of the European territories on the other side of the Pyrenees (especially Flanders and Italy) and those of the kingdoms of the Iberian Peninsula, which are the subject of this article.