Grusi, ethnolinguistic group among the inhabitants of northern Ghana and adjacent areas of Burkina Faso (formerly Upper Volta) and Togo. The linguistic groups and subgroups of the area are difficult to classify with certitude, but the Grusi languages make up a subbranch of the Gur (Voltaic) branch of the Niger-Congo language family. The difficulty in establishing distinct language boundaries is the result of a gradual and continuous migration of peoples that has produced a complex pattern of merged ethnic groups.
Population movements have been brought about partly through invasion and conquest by other peoples, such as the More-Gurma (Mõõre-Gurma) speakers from the east. Ecological pressure has also contributed to population movements. The area is one of dry savanna and is subject to frequent droughts. Agriculture by shifting cultivation contributes to the depletion and erosion of the soil, necessitating periodic relocation of groups to more productive lands. Crops include yams, millet, corn (maize), and cotton. The cattle, sheep, and goats that are kept are used more for marriage payments and ritual sacrifices than as a source of food. Crafts practiced in the area are often connected with agriculture and include metalworking, basketry, leatherworking, and pottery.
Contacts between members of some Grusi-speaking ethnic groups demonstrate a certain social intimacy combined with a need to regulate interactions. Isala and Kasena, for example, are known to trade insulting remarks in a joking spirit so as to reduce tension from past conflicts. Institutional ties among the peoples of the area are sometimes formed in ritual and political activities and through intermarriage.
Because there are a number of particular cultural traditions, the social organization of Grusi-speaking peoples varies. Descent-group membership, succession, and property inheritance are often through males, but among the Tampolense and Vagala the female line is used. The heads of lineages of relatives oversee livestock, farmland, and ancestral shrines. Political functions are generally not centralized, and each group can contain a number of independent chiefs. In the case of one group, the Isala, centralized political authority under chiefs was little emphasized before the advent of British colonial administration.