The main theories of nationhood are modernism, ethno-symbolism, and primordialism. This chapter focuses on the experimental approach of Benedict Anderson in his celebrated Imagined Communities. Primordialism rests on a fundamental supposition that nations derive from traditional, and implicitly authentic, forms of social organization. In primordialism the nation is postulated as a community of descent: a people claiming distinctiveness, and the right to rule themselves, on grounds of their common origin. There are further problems with the primordialist approach which cannot be brushed aside. One of its key components is a core religious institution, related to a messianic sense of destiny. A minority of modern states have populations defined by a strong claim to ethnic homogeneity, but this is easily attributable to historic isolation, closed polities, or an ideology of racial conquest. The modern states system has made it controversial to define a nation as a community of worth.