Septima Clark first heard of the NAACP while she was teaching on John’s Island from 1916-1919. There was no NAACP chapter on John’s Island, but a meeting was held in which various preachers came and spoke about what the NAACP was and what exactly it was trying to do. The superintendent was in attendance to collect dues and it was then that she decided to join the organization. In 1919, Clark returned to Charleston to teach sixth grade at Avery Normal Institute, a private academy for black children. In Charleston, she joined the Charleston Branch of the NAACP and began attending meetings regularly of the National Association for the Advancement of Colored People (NAACP). Under the guidance of Edmund Austin, the President of the local NAACP in Charleston, Clark took part in her first political action with the NAACP in Charleston. Despite the orders of her principal, Clark led her students around the city, going door-to-door, asking for signatures on a petition to allow black principals at Avery. She got 10,000 signatures in a day’s time and in 1920 black teachers were permitted. In 1920, Clark enjoyed the first of many legal victories when blacks were given the right to become principals in Charleston’s public schools, under the education board of aldermen of Charleston. Her participation in the NAACP was Clark’s first statement in political action. In 1945, Clark worked with Thurgood Marshall on a case that was about equal pay for white and black teachers led by NAACP in Columbia, South Carolina. The late-1940s proved to be a difficult time for Clark as she stood up with the NAACP’s aim of equalization to integration against many other members and activists.

During summers, Septima Clark began studies at Columbia University in New York, and at Atlanta University in Georgia with the landmark figure in the racial equality movement, W. E. B. Du Bois. Between 1942 and 1945, she received a bachelor’s degree from Benedict College, Columbia, SC and a master’s degree from Hampton (Virginia) Institute (now Hampton University). While earning her B.A., she was taking classes in the morning, teaching from noon to five in the afternoons, and taking more classes in the evenings. She was making 62.50 dollars a month in college and every summer she traveled to Maine to make more money. The NAACP in Columbia, SC, had approximately 800 members and all were black. The biggest NAACP impact during Clark’s time in Columbia was they sponsored a suit that won the equalization of teacher salaries. It was a huge win for the NAACP.[5] In 1947, Clark returned to Charleston to take care of her mother who had had a stroke. While caring for her mother Clark’s role as an educator and activist did not subside. During this time, she taught in the Charleston public schools, she was active with the YWCA, and served as membership chairperson of the Charleston NAACP. The YWCA was one of the few organizations in Charleston that was interracial. There were black and white branches. In 1956, Clark obtained the position of vice president of the Charleston NAACP branch. That same year, the South Carolina legislature passed a law banning city or state employees from being involved with civil rights organizations. Clark believed that a combination of relations, such as social and power relations, were a major contributor to schooling. Septima Clark was upfront in her refusal to leave the NAACP, and was thus fired from her job by the Charleston City School Board, losing her pension after 40 years employment. She soon found that no school in Charleston would hire her. A black teachers’ sorority held a fundraiser for her benefit, but no member would have their picture taken with her, fearing that they would lose their own jobs.

Around this time, Septima Clark was active with the Highlander Folk School in Monteagle, Tennessee. She first attended a workshop there in 1954. Myles Horton, the founder of Highlander, quickly hired her as the full-time director of workshops. Before long she was teaching literacy courses, drawing on her experience on John’s Island. “In a compressed week’s workshop, Clark promised to turn sharecroppers and other unschooled Negros into potential voters”. Highlander was one of the few interracial schools in the South at the time and Clark prospered as a teacher there. After being fired and unwelcomed in her hometown, Clark found Highlander to be a great community. In 1959, while she was teaching at Highlander she was arrested for allegedly “possessing whiskey”; however, these charges were later dropped and seen as false. Septima Clark and her cousin, Bernice Robinson, expanded and spread the program. They taught students how to fill out driver’s license exams, voter registration forms, Sears mail-order forms, and how to sign checks. Clark also served as Highlander’s director of workshops, recruiting teachers and students. One of the participants in her workshops was Rosa Parks. A few months after participating in the workshops Parks helped to start the Montgomery Bus Boycott. Additionally, many other women who took part in the Montgomery Bus Boycott attended Highlander, under the teaching of Clark. Upon seeing the success of Clark, Ella Baker traveled to Highlander as a representative of SCLC and observed to see if Clark’s program could be incorporated into SCLC’s Crusade for Citizenship.

U.S. President Jimmy Carter awarded Clark a Living Legacy Award in 1979. In 1987, her second autobiography, Ready from Within: Septima Clark and the Civil Rights Movement, Wild Trees Press, (1986), won the American Book Award. Septima P. Clark died December 15, 1987. In a eulogy presented at the funeral, the president of the Southern Christian Leadership Conference (SCLC) described the importance of Clark’s work and her relationship to the SCLC. Reverend Joseph Lowery asserted that “her courageous and pioneering efforts in the area of citizenship education and interracial cooperation” won her SCLC’s highest award, the Drum Major for Justice Award. She is buried at Old Bethel United Methodist Church Cemetery in Charleston, South Carolina. Clark had major relations to other black activists of the Civil Rights Movement, such as Booker T. Washington and W. E. B. DuBois. Washington and Clark both emphasized the importance of self-improvement before the importance of institutional reforms. DuBois and Clark agreed on the emphasis of education as the most important approach to the civil rights movement. Spetima Clark Public Charter School in Washington, DC is named in her honor.