Afonso Henriques and subsequent Portuguese kings ruled by divine right until a constitutional monarchy was established in the early nineteenth century. The early kings were assisted by a royal council composed of the king's closest advisers and friends from among the higher nobility and clergy. The royal council was staffed by a number of functionaries, such as the chancellor, who kept the royal seal and was the highest official in the land; the notary, who gave advice on legal matters; the scribe, who wrote the king's letters and documents (many early kings were illiterate); and the majordomo, who commanded the king's household guard.

When questions of exceptional importance arose, the king would convoke the cortes, an expanded royal council that brought together representatives of the three estates of the realm: nobility, clergy, and commoners. The first such cortes was called in 1211 at Coimbra in order to legitimate the succession of Afonso II, Afonso Henriques's grandson, to the throne, as well as to approve certain laws of the realm. After the Cortes of Leiria, which was convoked in 1254 by Afonso III, representatives of the self-governing settler communities began to attend. Cortes were convoked at the king's will and were limited to advising on issues raised by the king and presenting petitions and complaints. Resolutions passed by the cortes did not have the force of law unless they were countersigned by the king. Later, the cortes came to limit the power of the king somewhat, but gradually the monarchy became absolute. The cortes was convoked less and less frequently, and in 1697 it stopped being called altogether.

As to territorial administration, northern Portugal was subdivided into estates (terras), each a quasi-autonomous political and economic unit of feudal suzerainity governed by a nobleman (donatário) whose title to the land was confirmed by the king. Religious administration was carried out by the Roman Catholic Church, which divided the north into bishoprics and parishes. In the south, administration was the responsibility of the military orders: Templars, Hospitallers, Calatravans, and Knights of Saint James. In the center, administration fell to the monastic orders: Benedictines, Franciscans, and Dominicans. The towns and communities of settlers, as well as a certain amount of land around them, were owned by the king, who was responsible for regulating them.

The settler communities (concelhos) were each recognized by a royal franchise, which granted local privileges, set taxes, specified rights of self-government, and controlled the relationship among the crown, the concelho, and the donatário, if the community was located within a terra. Each concelho governed itself through an assembly chosen from among its resident "good men" (homens-bons); that is, freemen not subject to the jurisdiction of the church, the local donatário, or the special statutes governing Muslims and Jews. Each concelho was administered by a local magistrate, who was assisted by several assessors selected from among the homens-bons of the assembly. The tutelary power of the king was represented by an official (alcalde) appointed by the king, who was empowered to intervene in local matters on the king's behalf when necessary to ensure justice and good administration. The degree of self-government of these communities gradually declined as the monarchy became increasingly centralized.

During its formative stages, Portugal had three social classes: clergy, nobility, and commoners. By virtue of the religious fervor of the times, the clergy was the predominant class. It was the most learned, the wealthiest, and occupied the highest office in the realm: the chancellorship. The clergy comprised two categories; the bishops and parish priests of the regular church hierarchy and the abbots and monks of the religious and military orders. These two categories were divided into the higher clergy (bishops and abbots) and low clergy (priests and monks). The clergy enjoyed various privileges and rights, such as judgment in ecclesiastical courts according to canon law, exemption from taxes, and the right to asylum from civil authorities within their churches.

The next social class, the nobility, owed its privileged position above all to its collaboration with the king in the reconquest. The highest level among the nobility was made up of the "rich men" (homens-ricos) who owned the largest feudal estates, had private armies, and had jurisdiction over great expanses of territory. Below them were the lesser nobility, who held smaller estates and were entrusted with the defense of castles and towns but did not have private armies or administrative jurisdiction. Below the lesser nobility were the highest class of free commoners, the villein-knights, who maintained their own horses and weaponry, serving the king as required. These knights were often encouraged to settle in or near the colonial communities of the frontier where they were granted special privileges and organized raids against the Muslims for their own profit.

The commoners formed the bottom of the social strata. Among them the serfs were the lowest group. The most numerous group, they were bound by heredity to the estates of the crown, nobility, and clergy, where they were occupied in agriculture, stockraising, and village crafts. Serfs could become free by serving as colonists in the underpopulated territories in the south. The second lowest group consisted of the clients, that is, freemen who did not own property and received protection from an overlord in exchange for service. Above the clients were the villein-knights, who formed a stratum that merged the commoners with the nobility. Finally, outside the basic social structure were the slaves, usually Muslim captives, who tilled the lands of the military orders in the Alentejo.

Data as of January 1993