March
In Harper v. Virginia Board of Elections, 383 U.S. 663 (1966), the Supreme Court holds that state governments May not impose poll taxes in state elections.

Summer
Stokey Charmichael ousts John Lewis as the head of Student Non-Violent Coordinating Committee (SNCC). Radical separatist black activists, such as Carmichael, Hubert "Rapp" Brown, who replaced Carmichael as the head of SNCC in 1967, and the soon-to-be founders of the Black Panthers Huey Newton and Bobby Seale, begin overtly challenging Martin Luther King's leadership of the movement and his non-violent principles. The civil rights movement splinters from within. Black radicals reject integrationist strategies and call for a return to black control of local school districts in black neighborhoods under the banner of "black power."

October
The National Organization for Women (NOW) is founded in Washington, D.C., with Betty Friedan as its first president.

Huey Newton and Bobby Seale found the Black Panther Party for Self-Defense in Oakland, California.

December
In United States v. Jefferson County Bd. of Education, 372 F.2d 836 (5th Cir. 1966), Judge Minor Wisdom orders New Orleans school districts to abandon "freedom of choice" plans that have consistently failed to desegregate schools. The court orders the city to "undo the harm" of past desegregation by racially balancing the schools, using guidelines issued by the Department of Health, Education, and Welfare (HEW).