The Mississippi Freedom Democratic Party was a political party created in 1964 by black and white Mississippians, with assistance from the Student Nonviolent Coordinating Committee, to win seats at the 1964 Democratic Convention for a slate of delegates elected by disenfranchised black Mississippians and white sympathizers. It ultimately failed, but succeeded in dramatizing the violence and injustice by which the white power structure governed Mississippi and building pressure for the Voting Rights Act of 1965.

The official Mississippi state democratic party in 1964 was, like Democratic party organizations elsewhere in the Deep South, committed to defending white supremacy. It had two very powerful Senators, James Eastland and John Stennis, and five senior House members.

Yet by 1964 the official state party no longer supported the national Democratic party or the President, Lyndon B. Johnson, because of Johnson's work to pass the Civil Rights Act of 1964. State Party officials openly campaigned for the Republican candidate, Barry Goldwater, who was running strongly in the South on the strength of his opposition to civil rights laws.

Civil rights organizations had held a Freedom Vote in Mississippi in 1963 to demonstrate the desire of black Mississippians to vote; more than 90,000 people voted in mock elections pitting candidates from the Freedom Party against the official State Party Candidates. In 1964 organizers launched the Mississippi Freedom Democratic Party to challenge the all-white slate from the State Party. When Mississippi voting registrars refused to recognize their candidates the held their own primary, selecting Fannie Lou Hamer, Annie Devine, and Victoria Gray to run for Congress and a slate of delegates to represent Mississippi at the 1964 national Democratic convention.

Their presence in Atlantic City, New Jersey was very inconvenient, however, for the convention organizers, who had planned a triumphal celebration of the Johnson Administration’s achievements in civil rights, rather than a fight over racism within the Democratic Party itself. Johnson was also worried about the inroads that Barry Goldwater’s campaign was making in what had previously been the Democratic stronghold of the "Solid South" and the support that George Wallace had received during the Democratic primaries in the North. Other all-white delegations from other Southern states had threatened to walk out if the all-white slate from Mississippi were not seated.

Johnson could not, however, prevent the MFDP from taking its case to the Credentials Committee, where Fannie Lou Hamer testified about the beatings that she and others were given and the threats they faced for trying to register to vote. Turning to the television cameras, Hamer asked, "Is this America?"

Johnson attempted to preempt coverage of Hamer's testimony by calling a hastily-scheduled speech of his own. That did not, however, stop the networks from covering her story as part of the evening news. Her testimony had created enough uproar that Johnson offered the MFDP a "compromise": they would receive two non-voting at-large seats, while the lily-white delegation sent by the official Democratic Party would take its seats.

Johnson used all of his resources, mobilizing Walter Reuther, one of his key supporters within the liberal wing of the Democratic Party, and his Vice-Presidential nominee Hubert Humphrey, to put pressure on Martin Luther King, Jr and other mainstream civil rights leaders to bring the MFDP around, while directing J. Edgar Hoover to put the delegation under surveillance.

The MFDP, however, rejected the compromise. As Aaron Henry, then the President of the NAACP's Mississippi affiliate, stated:

"Now, Lyndon made the typical white man's mistake: Not only did he say, "You've got two votes," which was too little, but he told us to whom the two votes would go. He'd give me one and Ed King one; that would satisfy. But, you see, he didn't realize that sixty-four of us came up from Mississippi on a Greyhound bus, eating cheese and crackers and bologna all the way there; we didn't have no money. Suffering the same way. We got to Atlantic City; we put up in a little hotel, three or four of us in a bed, four or five of us on the floor. You know, we suffered a common kind of experience, the whole thing. But now, what kind of fool am I, or what kind of fool would Ed have been, to accept gratuities for ourselves? You say, Ed and Aaron can get in but the other sixty-two can't. This is typical white man picking black folks' leaders, and that day is just gone."

Hamer put it even more succinctly:

"We didn't come all the way up here to compromise for no more than we’d gotten here. We didn't come all this way for no two seats, 'cause of all us is tired."

The MFDP kept up its agitation within the Convention, however, even after it was denied official recognition. When all but three of the "regular" Mississippi delegates left because they refused to pledge allegiance to the Party, the MFDP delegates borrowed passes from sympathetic delegates and took the seats vacated by the Mississippi delegates, only to be removed by the national Party. When they returned the next day to find that convention organizers had removed the empty seats that had been there yesterday, they stayed to sing freedom songs.

The 1964 convention disillusioned many within the MFDP and the civil rights movement, but it did not destroy the MFDP itself. The MFDP continued to organize to replace the "regular" State Party, challenging the right of the Mississippi delegation to the House of Representatives to hold office on the ground that Mississippi's systematic denial of blacks' voting rights made their election unconstitutional. It elected Robert Clark to the Mississippi Legislature in 1967, then made up part of the "Loyalist" slate that ousted the white supremacist "regular" delegation at the 1968 Democratic Convention in Chicago . Even then the "Regulars" did not disappear entirely, but continued to run state Democratic Party primary elections while the National Democratic Party recognized the "Loyalists."

The MFDP became more radical after Atlantic City, inviting Malcolm X to speak at its founding convention and opposing the war in Vietnam. But while its efforts eventually helped elect more black office-holders in Mississippi than in any other state, the MFDP itself found it harder to keep its organization afloat. It slowly faded out of existence after its alliance with the more mainstream forces in the "Loyalist" Democrats.