Despite its small population, Laos has no less than 68 tribal groups. About half are Lao Loum, "lowland Lao" who live in the Mekong valley. Officially, this group includes the Lao Tai, who are subdivided into numerous subgroups. Lao Theung (20-30%), or "upland Lao", live on mid-altitude slopes (officially defined as 300m to 900m), and are by far the poorest group, formerly used as slave labor by the Lao Loum.

The label Lao Sung (10-20%) covers mostly Hmong and Mien tribes who live higher up. There are also an estimated 2-5% Chinese and Vietnamese, concentrated in the cities. Laos is officially Buddhist, and the national symbol, the gilded stupa of Pha That Luang, has replaced the hammer and sickle even on the state seal. Still, there is a good deal of animism mixed in, particularly in the baasii (also baci) ceremony conducted to bind the 32 guardian spirits to the participant's body before a long journey or other significant undertaking.

Lao custom dictates that women must wear the distinctive phaa sin, a long, patterned skirt, although tribal groups often have their own clothing. The conical Vietnamese-style hat is also a common sight. These days men dress Western style and only don the phaa biang sash on ceremonial occasions