When did "The Sixties", as opposed to the 1960s decade happens. In some ways, they began in the '50s, and in others, they're still around today, but overall I would say "The Sixties" began when John F. Kennedy was shot and ended with the Kent State shootings.

Yeah, alot of people feel JFK's assassination in late '63 more or less ended the feel of the '50s, and I pretty much agree (plus, a few months later, the Beatles on Ed Sullivan kinda jumpstarted the pop cultural '60s), but I don't think the '50s totally ended until the Summer of Love in '67.

Late '63-1966/early '67 is almost its own little era in a way. Some of the songs and overall attitude is still oldies/50s-esque in a reduced extent. But that summer is when stuff started getting into the psychedelic/Hippie/counterculture/drug use era. I'd also agree the "peak" 60s ended in '70 or maybe '71, but pieces of it were around up to '75.

Actually, the '60s were pretty long if you think about it (even if their peak was short). ;)

The Sixties began with JFK's death and ended with the deaths of Martin Luther King Jr. and Bobby Kennedy. 

Yeah, the 60s began with J.F.K.'s assasination as well as Marilyn Monroe's death, both occuring in 62 and 63 respectively. Sort of ended the 'Golden Age' of Classicism/Romanticism, and heralded a dionysian age, the pre-cursor to the so called 'Age of Aquarius' as many were touting back in the 60s. Yet, as I've said, in many ways the societal norms for the older generation did not change much til the very late 60s/70s. The beginning of the Vietnam War (Gulf of Tonkin) about 1964 and Beatlemania around the world in 1964 are also markers.