Sultan Mohammed V assumed the title of King in 1957. After French authority was removed, the Sultan as King became an absolute ruler over a country with no constitutional institutions of any kind. This situation increased the difficulty of moving toward a parliamentary form of government, which the nationalist movement desired. The first three governments after independence were formed to a large extent on party lines, although the King retained control of the army, the police force and the central administration. In forming the fourth government in 1960, the King abandoned the attempt to respect party claims. Ministers were selected instead for their “loyalty, integrity and ability,” and King Mohammed V himself became premier, naming his son as his day-to-day deputy.

At Mohammed’s death in 1961, the throne passed to his son Hassan II. This popular leader cemented his place in Moroccan hearts and minds by staging the Green March into the Western Sahara, an area formerly held by Spain. With a force of 350,000 volunteers, Hassan's followers overcame the indigenous Sahrawis to claim the mineral-rich region as their own.

By the 1960s it had become clear that the 100,000 or so inhabitants of the 'territory' wanted independence. Western Sahara's Popular Front for the Liberation of Saguia al-Hamra and Rio de Oro (Polisario) didn't take kindly to the invasion and embarked on a long and gruesome war of independence against Morocco. Despite attempts at international mediation the issue remains unresolved. While the Moroccan masses applauded the southern invasion, it left nearby Algeria almost as unhappy as the Western Saharans themselves. Morocco's relations with this particular war-torn neighbour have been poor ever since.

A royal charter was implemented by Hassan, whereby a constitutional monarchy was established on the approval by referendum of a constitution in December 1962. The nation’s first general elections were held in 1963 and the first parliamentary government was formed afterward. King Hassan II died in July 1999 and was succeed by his son, Mohammed VI.