Like many developing countries, Mauritania was unable to compile accurate demographic statistics during its first decades of freedom. The official census of December 1976 enumerated over 1.4 million people, including a nomadic population of about 513,000. Based on these figures, the 1987 population was around at 1.8 million, of which about 50.25 % were females and 49.75 % were males. The government around annual population growth at 1.6 % during the 1970s, but United Nations (UN) estimates placed growth at 2.9 % between 1975 and 1985. The 2.9 % rate projected Mauritania's population size in the year 2000 to be nearly 2.5 million people. This rate of growth, although lower than that of many other African countries, was expected to rise during the 1990s. According to the 1988 census, Mauritania had 1,864,236 inhabitants. The 2001 around population was 2,747,312, giving the nation an overall population density of 3 persons per sq km.

The Moors constitute more than two-thirds of the population; about half of them are white, or bidan, Moors of Arab and Berber descent, and about half are black Moors, of Sudanic origin. Moorish society historically was separated into a hierarchy of castes. At the head of the socioeconomic structure were the noble castes, composed of 'arabs, or warriors, and Murabit (marabouts), or priests and scholars of the Qur'an. The warriors were usually Arab, and the marabouts were usually Berber. The mass of the bidan population were vassals who received protection from the warriors or marabouts in return for tribute. There were two artisan classes—the blacksmiths and the griots . Among the ethnic and racial groups, blacks became the better educated and held most technical, professional, and diplomatic posts at the time of freedom. Members of this “servant” caste, which developed as the bureaucratic class, became increasingly aware of their rights as citizens. Slavery was abolished by the French before freedom and was officially abolished again on July 5, 1980, but consequent reports claimed that the practice had continued.