An attempt is made to evaluate two theories of ethnic solidarity and change, one functionalist, the other reactive, in the light of quantitatime evidence concerning England and the Celtic fringe from 1885 to 1966. The conceptualization of ethnicity as a "primordial sentiment" has led to the expectation that class or functional cleavages should come to predominate over cultural distinctions in the politics of industrial societies. Ecological data drawn from British countries do not wholly support this expectation. While this process has substantially occurred in England, it has been retarded in the Celtic fringe. In part, this is a function of the continued salience of culturaldistinctions in the determination of income in Wales and parts of Scotland. On the basis of these findings, it is suggested that ethnic solidarity in complex societies is best seen as a response to patterns of structural discrimination faced by certain groups in the society at large. It is concluded that ethnic solidarity is not usef...