Most people live in central villages, with second houses near their crops. Sweet potatoes and fish are the main foods. Taro is the second starch food in the north-west, yams in the southeast. A wide variety of traditional and introduced foods are grown. In swamp areas, sago is an emergency food.
Most people base clan membership and inheritance rights on their mother's family line.
The crafts and customs of Buka and northern Bougainville are more complex than in the south. Their men's houses, carving, and weapons are more fully decorated. Their initiation rites are more complicated. The upei , a symbol on the provincial flag, is a tradition of the north. It is a tall, woven hat which young men wore between initiation and marriage.