The Obamas and the Clintons placed a wreath of white flowers in front of the Kennedy's grave at Arlington National Cemetery in Virginia. Once the wreath was in place, a single bugler played "Taps" as the Obamas and the Clintons stood with their hands over their hearts.
They also spoke with members of the Kennedy family and guests who attended the 50th anniversary commemoration. The anniversary date is Friday this year.
Fifty years ago on Nov. 22, 1963, Lee Harvey Oswald fired from the Texas School Book Depository as the presidential motorcade snaked through Dealey Plaza in Dallas, killing the first Catholic president two years into his term.
A 10-month investigation by the Warren Commission concluded Kennedy was assassinated by Oswald, who acting alone; and that Jack Ruby also acted alone when he killed Oswald before he could stand trial.
Also Wednesday, Obama awarded 16 Americans the Presidential Medal of Freedom Award, the nation's highest civilian honor that was established by Kennedy a half-century ago. President Clinton was among the recipients.