Having established the boundaries of the national territory, asserted their authority over the church and nobility, and gained control over the resources of the military orders, Portuguese kings began to turn their attention to the economic, cultural, and political development of the realm. This was especially true of King Dinis, who is referred to by the Portuguese as The Farmer (O Lavrador) because of his policies designed to encourage agricultural development. He decreed that nobles would not lose their standing if they drained wetlands, settled colonists, and planted pine forests. The pine forests were to produce timber for the shipbuilding industry, which Dinis also encouraged, the crown having already at that time begun to look toward the sea for future fields of conquest.

Dinis chartered many settlements of colonists on lands conquered from the Muslims and authorized the holding of fairs and markets in each of these, thereby creating a national economy. He laid the basis for Portugal's naval tradition by bringing the Genoese, Emmanuele Pessagno (Manuel Peçanha in Portuguese) to Portugal in 1317 to be the hereditary admiral of the Portuguese navy. Maritime commerce was encouraged when Dinis negotiated an agreement with Edward II of England in 1303 that permitted Portuguese ships to enter English ports and guaranteed security and trading privileges for Portuguese merchants. Dinis provided the impetus for the development of Portuguese as a national language when he decreed that all official documents of the realm were to be written in the vernacular. Finally, Dinis stimulated learning when, in 1290, he founded an academic center similar to the "General Studies" centers that had been created in León and Aragon. In 1308 this center was moved to Coimbra where it remained, except for a brief time between from 1521 to 1537, and became the University of Coimbra, Portugal's premier institution of higher learning.

Afonso IV (r.1325-1357) continued his father's development policies. He also improved the administration of justice by dismissing corrupt local judges and replacing them with judges he appointed. When a large Muslim army landed on the peninsula in 1340, Afonso IV allied himself with the king of Castile, Alfonso XI, and the king of Aragon in order to do battle against this threat to the Christian kingdoms. Afonso sent a fleet commanded by Manuel Peçanha to Cádiz and marched overland himself to meet the Muslim army, which was destroyed at the Battle of Salado.

When Afonso's grandson and heir, Fernando I (r.1367-83), ascended the throne, the economic productivity of the country had been so greatly disrupted by the plague that ravaged the country in 1348 and 1349 that he found it necessary to take measures to stimulate food production. In 1375 he promulgated a decree, called the Law of the Sesmarias, which obliged all landowners to cultivate unused land or sell or rent it to someone who would. The law also obligated all who had no useful occupation to work the land. This decree had its intended effect and led to the rebuilding of the country's wealth. Fernando also st30c stimulated the development of the Portuguese merchant fleet by allowing all shipbuilders who constructed ships of more than 100 tons to cut timber from the royal forests and by exempting the owners of these ships from the full tax on the exports and imports of their first voyage. He also established a maritime insurance company into which owners of merchant ships of more than fifty tons paid 2 percent of their profits and from which they received compensation for shipwrecks.

Data as of January 1993