In the 1950s, African Americans won a huge victory in the effort to desegregate schools. However, the victory did not lead to immediate desegregation. The victory, in Brown v. Board of Education, was the main success while the slow pace of implementation of Brown was the major setback.
After World War II, the NAACP Legal Defense Fund worked to undermine the idea of separate but equal in public education. It started out by challenging the doctrine at the post-graduate level. It litigated cases arguing that “separate but equal” law schools were not really equal (Sweatt v. Painter) and that a graduate school should not be allowed to keep a black student separate from the white students (McLaurin v. Oklahoma State Regents). It won those cases. A few years later, in 1954, it won a tremendous victory when the Supreme Court ruled in Brown that segregated public K-12 schools were unconstitutional. This was a major success because it destroyed the doctrine of separate but equal in public education.
However, civil rights activists also experienced a major setback in this decade. When the Supreme Court made its decision in Brown, a wave of opposition arose from whites in the South. These supporters of segregation worked hard to slow the implementation of desegregation. Some places went so far as to shut down public schools that were being required to desegregate. Because of this opposition, desegregation went very slowly. This was the main setback with respect to ending segregated education in the 1950s.