The Student Nonviolent Coordinating Committee (SNCC) was one of the leading civil rights organizations early in the 1960s. When the SNCC was doing this, it was responsible for some of the major events of the Civil Rights Movement. Things they did included setting up the Freedom Summer of voters' registrations in Mississippi. They also participated in the famous March on Washington.
But then, they started to lose their patience. They came to be led by more radical people such as Stokeley Carmichael and became more of a Black Power organization. This change happened in large part because race relations were getting worse (riots, etc) and SNCC felt they were not pushing hard enough for true equality.