The basic hypothesis offered here is that the outbreak of mass violence was an almost inevitable consequence of the major population changes that American Negroes have been undergoing in recent years. (1) The most important of these population changes have been the movement from the South to the North, the movement from rural areas to the largest metropolitan centers, and the rapid rise in the average level of education, in combination with the extreme youth of the black population. (2) Individuals from the "new" background (the young natives of Northern cities) were considerably more active in the riots than were those from the "old" background (the older migrants from the South). (3) Two principal socio-psychological mediators were offered to explain this finding: the attitudinal and behavioral effects of changes in black racial socialization, and of differential comparison levels. (4) Evidence was presented that early racial socialization produces predispositions that tend to endure through life. For Negroes, contemporary Northern socialization is generally thought to involve more abrasive and assertive norms of behavior toward white authority and white-dominated social institutions than does Southern socialization, particularly that of earlier times. Data from the Watts riot suggest that young Northern natives were more disaffected from the political structure, and were more likely to endorse violence, than were older and migrant residents. The disaffected were also considerably more likely to have been involved in the riot. (5) The Northern natives also appear to feel more deprived than do the Southern blacks. And dissatisfaction in this sense was related to participation in the riot. It goes without saying that no single explanation or set of explanations is likely to be adequate for such complex and massive social events as the recent race riots. However, the evidence presented here suggests that fundamental and irreversible social changes in the location and characteristics of the black population have produced important social-psychological changes within individual blacks. These, in turn, have increased enormously the probability that blacks will respond to white racism with intransigence, vigorous protest, and even violence. The further implication is that the apparently centrifugal movement represented by the Deacons, the Black Panthers, and the wavering attachment of some young militants to the American political and economic system are not epiphenomena; nor are they merely representative of a small minority's peculiar and disreputable ideas. They symbolize, although in more extreme form, the direction being taken by young ghetto natives throughout the country. Our data suggest that the direction and thrust of this movement are irreversible without extreme measures that white Americans presumably would not condone. The question appears to be whether or not institutional America, and the white population more generally, are prepared to accept the new "black man" as a replacement for the old "Negro." There seems to be little chance that the latter will return. [ABSTRACT FROM AUTHOR]