A diverse international movement which sought to reformulate traditional left-wing politics in the 1960s, New Left activism culminated in the widespread upheavals of 1968, "the year of the barricades," when political dissent erupted around the developed world against the backdrop of a major escalation of American activity in Vietnam, the assassinations of Martin Luther King and Robert Kennedy, and the Soviet invasion of Czechoslovakia. The May 1968 demonstrations in France, which briefly united students and workers in a series of direct confrontations with French government authority, have acquired a near legendary status in popular historical assessments of the New Left. But it was the United States, largely because of the War in Vietnam and the struggle for black civil rights, which formed the epicenter of New Left politics throughout the decade.

Never a cohesive movement as such, the American New Left was a loose coalition of dissenting activist...