Kennedy's record on civil rights was something of a mixed bag. Initially, his approach to the question was piecemeal. As a Democrat, Kennedy knew that he was reliant on Southern white supremacists in Congress to advance his legislative program. He'd also need Southern votes for re-election in 1964.
Though personally sympathetic to the cause of civil rights, Kennedy tended to react to events as and when they happened, rather than show leadership on the issue. Kennedy thought that by working behind the scenes and striking deals with Southern politicians, he could promote civil rights without undermining either his Presidency or his chances of re-election.
The failure of this approach was seen in the case of James Meredith, an African-American student who attempted to enrol at the University of Mississippi. Despite reaching what he thought was an accommodation with the state's white supremacist governor, violent segregationists prevented Meredith from enrolling at the university.
Even this very public humiliation did nothing to change Kennedy's piecemeal approach to civil rights. He continued to submit watered-down proposals to Congress that failed to address key demands of civil rights campaigners, such as equal access to public facilities.
It was only after the violent attacks on civil rights marchers in Birmingham that Kennedy started to take action. He went on national TV and announced to the nation that he would send comprehensive civil rights legislation to Congress. But five months later, at the time of Kennedy's assassination, still no legislation had been passed.
Kennedy's failure on civil rights was by no means an absolute one. It's rather that he grasped the full moral import of the issue much later than he ought to have done, slowing down the pace and extent of civil rights reforms.