It was only four days after Howard's speech that Rosa Parks, who was also in the audience, refused to comply with the Jim Crow law that required her to give up her seat to a white man. The Montgomery Bus Boycott, led by King, soon followed. It lasted for 382 days. (The number of days is often quoted as 381, but that overlooks the fact that 1956 was a leap year.) According to the ProQuest article, the Montgomery Bus Boycott lasted for 386 days. The situation became so tense that King's house was bombed. King was arrested during this campaign, which ended with a United States Supreme Court decision outlawing racial segregation on intrastate buses and all public transport.

Following the campaign, King was instrumental in the founding of the Southern Christian Leadership Conference (SCLC) in 1957, a group created to harness the moral authority and organizing power of black churches to conduct nonviolent protests in the service of civil rights reform. King continued to dominate the organization until his death. The organization's nonviolent principles were criticized by some blacks and challenged by the Student Nonviolent Coordinating Committee (SNCC).

The SCLC derived its membership principally from black communities associated with Baptist churches. King was an adherent of the philosophies of nonviolent civil disobedience used successfully in India by Mahatma Gandhi, and he applied this philosophy to the protests organized by the SCLC. The Chicago Daily Tribune states that Gandhi's nonviolent techniques were useful to King's campaign to correct the civil rights laws implemented in Alabama (ProQuest: "New Sitdowns Stir Violence in Tennessee") Author Unknown, The Chicago Daily Tribune, April 12, 1960, retrieved March 11, 2006. The FBI began wiretapping King in 1961, fearing that communists were trying to infiltrate the civil rights movement, but when no such evidence emerged, the bureau used the incidental details caught on tape over six years in attempts to force King out of the pre-eminent leadership position. Garrow, op.cit. p.126.

Pacifist A. J. Muste, the executive director of the Fellowship of Reconciliation, served as an advisor to Martin Luther King Jr. King correctly recognized that organized, nonviolent protest against the racist system of southern segregation known as Jim Crow laws would lead to extensive media coverage of the struggle for black equality and voting rights. Indeed, journalistic accounts and televised footage of the daily deprivation and indignities suffered by southern blacks, and of segregationist violence and harassment of civil rights workers and marchers, produced a wave of sympathetic public opinion that made the Civil Rights Movement the single most important issue in American politics in the early-1960s.

Martin Luther King Jr., after his arrest in February of 1956, at the age of 27. He had been arrested during the Montgomery Bus Boycott. The mug shot was found in July, 2004, during the cleaning out of a storage room at the Montgomery County Sheriff's Department. Someone had written "DEAD" twice on the picture, as well as 4-4-68, the date King was killed, though it is not known who wrote it.

King organized and led marches for blacks' right to vote, desegregation, labor rights and other basic civil rights. Most of these rights were successfully enacted into United States law with the passage of the Civil Rights Act of 1964 and the Voting Rights Act of 1965.

King and the SCLC applied the principles of nonviolent protest with great success by strategically choosing the method of protest and the places in which protests were carried out in often dramatic stand-offs with segregationist authorities. Sometimes these confrontations turned violent. King and the SCLC were instrumental in the unsuccessful protest movement in Albany, in 1961 & 1962, where divisions within the black community and the canny, low-key response by local government defeated efforts; in the Birmingham protests in the summer of 1963; and in the protest in St. Augustine, Florida, in 1964. King and the SCLC joined forces with SNCC in Selma, Alabama, in December 1964, where SNCC had been working on voter registration for a number of months.