Living in the Truong Son range, the Co-tu practise slash-and-burn cultivation and dig holes to plant seeds. Apart from rice, they practise animal husbandry, cloth weaving and basketry. Food gathering, hunting and fishing are also very common. The exchange of products is carried out by barter. In the Co-tu village, the houses are set out in the form of an ellipse. In the middle of the village is the rong (communal house), a large and beautiful building which towers over all the other dwellings. This house is the place for the reception of guests, to hold meetings, rituals and cultural performances. It is also here that the elders spend most of their time recounting their memories.

Co-tu attire is simple. Men wear loincloths and leave their upper torsos naked. Women wear skirts and short vests. In winter they wear a piece of cloth.

The popular ornaments comprise necklaces, bracelets and earrings. Traditional customs such as tattooing face and body, filing teeth and men wearing their hair long, tied in a chignon have gradually declined.

The Co-tu's festival costume.

Patriarchy prevails among the Co-tu. The children take the family name of the father. The right of inheritance is reserved for sons only. Each Co-tu lineage has its private name. Every one in each lineage must obey a certain taboo. Tales are written about the lineage's origin and its taboo. All people of a lineage are responsible for mutual help. The dead are buried close to one another in the village burial ground. The Co-tu build funeral houses on the grave and set many wood statues around it. Anniversaries of death or grave-cleaning do not exist among the Co-tu.

According to custom, cross-marriage between the two lineages are forbidden. If a man of lineage A marries a woman of lineage B, a man of B is not allowed to marry woman of A. He must find his wife from other lineages. If the husband dies, the wife is allowed to marry his brother and vice versa. Marriage by purchase is a common practice. After the wedding, the bride comes to live in her husband's house. Monogamy is popular, but some rich men have several wives.

Every year, the Co-tu hold large and small rituals worshipping genies to pray for good luck and health and especially for bumper crops. The rituals are held mainly within families but some big rites are held by all the people of the village, in particular the buffalo-stabbing rite.