King came from a family steeped in the tradition of the Southern black ministry: both his father and maternal grandfather were Baptist preachers. At the age of 15 he entered Morehouse College, Atlanta, under a special program for gifted students, receiving his B.A. in 1948. As an undergraduate his earlier interests in medicine and law were eclipsed by a decision in his senior year to enter the ministry, as his father had urged. Spending the next three years at Crozer Theological Seminary in Chester, Pa. (bachelor of divinity, 1951), King first became acquainted with Mohandas Gandhi's philosophy of nonviolence as well as with the thought of contemporary Protestant theologians. He was elected president of the student body and was graduated with the highest academic average in his class. From Crozer he went to Boston University (Ph.D., 1955), where, in seeking a firm foundation for his own theological and ethical inclinations, he began to focus his attention on conceptions of the relationship of man to God. In his doctoral dissertation, "A Comparison of the Conceptions of God in the Thinking of Paul Tillich and Henry Nelson Wieman," his conclusions were fairly Niebuhrian. King himself conceived of God as an active, personal entity; man's salvation was to be found neither in the quest for social progress nor in the unaided power of reason; faith in God's guidance was the essential thing.

The first signs of opposition to King's tactics from within the civil-rights movement surfaced during the March 1965 demonstrations at Selma, Ala., which were aimed at dramatizing the need for a federal voting-rights law that would provide legal support for the enfranchisement of blacks in the South. King organized an initial march from Selma to the state capitol building in Montgomery but did not lead it himself; the marchers were turned back by state troopers with nightsticks and tear gas. He determined to lead a second march, despite an injunction by a federal court and efforts from Washington to persuade him to cancel it. Heading a procession of 1,500 marchers, black and white, he set out across Pettus Bridge outside Selma until the group came to a barricade of state troopers. But, instead of going on and forcing a confrontation, he led his followers in kneeling in prayer and then unexpectedly turned back. This decision cost King the support of many young radicals who were already faulting him for being too cautious. The suspicion of an "arrangement" with federal and local authorities--vigorously but not entirely convincingly denied--clung to the Selma affair. The country was nevertheless aroused, resulting in the passage of the Voting Rights Act of 1965.

Throughout the nation, impatience with the lack of greater substantive progress encouraged the growth of black militancy. Especially in the slums of the large Northern cities, King's religious philosophy of nonviolence was increasingly questioned. The rioting in the Watts district of Los Angeles (August 1965) demonstrated the depth of the urban race problem. In an effort to meet the challenge of the ghetto, King and his forces initiated a drive against racial discrimination in Chicago at the beginning of the following year. The chief target was to be segregation in housing. After a spring and summer of rallies, marches, and demonstrations, an agreement was signed between the city and a coalition of blacks, liberals, and labour organizations, calling for various measures to strengthen the enforcement of existing laws and regulations with respect to housing. But this agreement was to have little effect; the impression remained that King's Chicago campaign was nullified partly because of the opposition of that city's powerful mayor, Richard J. Daley, and partly because of the unexpected complexities of Northern racism.

In Illinois and Mississippi alike, King was now being challenged and even publicly derided by young black power enthusiasts. In the face of mounting criticism, King's response was to broaden his approach to include concerns other than racism that were equally detrimental to his people's progress. On April 4, 1967, at Riverside Church in New York City and again on the 15th at a mammoth peace rally in that city, he committed himself irrevocably to opposing the United States' involvement in the Vietnam War. Once before, in early January 1966, he had condemned the war, but official outrage from Washington and strenuous opposition within the black community itself had caused him to relent. He next sought to widen his base by forming a coalition of the poor of all races that would address itself to such economic problems as poverty and unemployment. It was a species of populism, seeking to enroll janitors, hospital workers, seasonal labourers, and the destitute of Appalachia, along with the student militants and pacifist intellectuals. His endeavours along these lines, however, did not engender much support in any segment of the population.

His plans for a Poor People's March to Washington were interrupted in the spring of 1968 by a trip to Memphis, Tenn., in support of a strike by that city's sanitation workers. On April 4 he was killed by a sniper's bullet while standing on the balcony of the motel where he and his associates were staying. On March 10, 1969, the accused white assassin, James Earl Ray, pleaded guilty to the murder and was sentenced to 99 years in prison.