Laos is a predominantly rural country.

The most recent government census of 2005 reveals a total population as 5,609,997, and although a detailed breakdown of this figure is not available at the time of writing, the previous census of 1995 showed that approximately 85 per cent of the total population live in rural areas.

According to the 2005 census, the largest centres of population are Vientiane Prefecture (695,473) and the provinces of Savannakhet (824,662), Champassak (603,880), Luang Prabang (405,949), Vientiane (386,558) and Khammouane (336,935).

The population of Laos has been significantly depleted over the past half century by warfare and mass exodus of refugees, and the current population density of some 25 people per square kilometre is one of the lowest in Asia. Another legacy of the country's turbulent history is that females still outnumber males by c 2:1. The Lao government is currently encouraging repopulation, and a large proportion of its population is currently made up of children.

One of South East Asia's most ethnically diverse countries, Laos has long defied the best efforts of anthropologists and linguists to classify its complex array of ethnicities and sub-ethnicities, many of which utilise several different names and synonyms given to them by the government or by other ethnic groups.

In the 1970s the Lao government began to classify its ethnic minorities according to the simple threefold designations Lao Loum (‘Lowland Lao’, corresponding to Lao, Lu, Phuan and other Tai-speaking Austro-Thai language family peoples), Lao Theung (‘Upland Lao’, embracing all Austro-Asiatic language family peoples) and Lao Soung (‘Highland Lao’, comprising Hmong-Mien peoples of the Austro-Thai language family and all Sino-Tibetan language family peoples). However, although this classification system is still quoted widely by civil servants and in many books on Laos, it is no longer given official credence; a more universally accepted method of organisation classifies Lao ethnic groups according to the three great language families - Austro-Thai, Austro-Asiatic and Sino-Tibetan.

According to the government census of 1995, the so-called Lao Loum or 'Lowland Lao' made up just over 3.1 million or 68 per cent of the then total population of 4.58 million. Of these just under 2.4 million (52 per cent of the total population) could strictly be designated as ethnic Lao; the remaining 700,000 (15 per cent of the total population) comprised various other Northern, South Western and as yet Unclassified Tay-Tai speaking peoples. Of the remaining 1.48 million Lao citizens, just over 1 million (22 per cent of the total population) comprised Austro-Asiatic Mon-Khmer peoples (designated by the government as Lao Thueng or 'Upland Lao'), just over 400,000 (9 per cent of the total population) were Lao Soung or 'Highland Lao' (Hmong, Yao, Haw, Akha, Ha Nhi, Kado, Kongsat, La Hu, Lolo, Phanna, Phunoi, Poussang and Si La) and around 45,000 (1 per cent of the total population) ethnic Vietnamese and Chinese.

More recent estimates suggest that out of a total population of 5.6 million (2005) there are now over 3 million ethnic Lao and around 2.6 million other cultural distinct ethnic people, including other Tay-Tai speakers.

The most numerically significant of the non-Lao ethnic groups in Laos are the Khmu (500,957, 1995), Hmong (315,465, 1995), Lu (119,191, 1995), Phuan (115,000, J Schliesinger estimate 2001), So (102,000, SIL estimate 1993), Katang (95,440, 1995), Akha (66,108, 1995), Tai Dam (65,000, J Schliesinger estimate 2000) and Bru (64,000, SIL estimate 1993).