It was a very good year, but as George Harrison admits, 1967 "did take about 50 years to complete." Some highlights: "Sgt. Pepper," the Summer of Love, psychedelic explosions and spiritual expansions, the Monterey Pop Festival, Armies of the Night camped out at the Pentagon, and of course, lots and lots of great music from the Beatles, the Rolling Stones, Bob Dylan, the Byrds, the Grateful Dead, Jefferson Airplane, Otis Redding and Jimi Hendrix, among others.

This social, sexual and musical revolution is examined, and celebrated, in "It Was 20 Years Ago Today," a two-hour documentary produced by Britain's Granada Television to celebrate the 20th anniversary of the release of "Sgt. Pepper's Lonely Hearts Club Band" (tonight at 9 on WETA and WHMM). All right, technically we're talking 20 years ago June 1, but while the classic album serves as an anchor and reference point, "Today" is much more than musical nostalgia or a Beatles memorial. It's a thoughtful, expansive look back at the times, the dreams, the rude realities and the untarnished aspirations of many of its key players.

"If you can remember the '60s, you really weren't there," says Jefferson Airplane founder Paul Kantner, but the producers have lined up some eloquent testimonials from key participants -- poet and social guru Allen Ginsberg, who gives a lovely song-by-song synopsis of "Sgt. Pepper"; Abbie Hoffman, still cynical after all these years; Tim Leary, the guru of LSD; assorted yippies, hippies and diggers, including actor Peter Coyote, once a counterculture playwright and participant and apparently still a noncynical champion of '60s values; Paul McCartney, far less flippant than usual. The best interview, though, is with Harrison, who may have once been the Quiet Beatle, but who here offers trenchant observations about the times when they were a-changin' and the people when they've a-changed.

There are also scads of contemporary film and television clips providing a bracing historical overview. The clips are musical (Pink Floyd doing "Interstellar Overdrive," a thin Steve Stills singing "For What It's Worth," a teen-aged Janis Ian doing "Society's Child," Jerry Garcia with black hair); social (be-ins and happenings, drug users seeking alternate realities); and political (the Levitation of the Pentagon, the emerging opposition to the war in Vietnam).

One sees the generation gap defining itself, often in amusing ways: Haight-Ashbury bus tours offering booklets like "The Language of the Hippies"; a stone-faced Leonard Bernstein quoting Bob Dylan -- "Something's happening and you don't know what it is, do you, Mr. Jones?" -- and adding, "You know who Mr. Jones is, don't you? Us!" Indeed.

One comes away from "It Was 20 Years Ago Today" with a remembrance of the invitations that defined the era. Invitations not just to "feed your head" or "turn on, tune in, drop out," but to participate in a new community, to explore changes and exchanges, to experiment, to join in a "tide of playfulness." The end of the program finds the Beatles addressing a worldwide audience with their newest song, "All You Need Is Love." Looking back, Harrison, McCartney, Coyote and others agree it's still a tenable position, though justice, awareness, truth and energy may be just as important.

The flower children may be long gone, but their consciousness still blooms, and this show proves that the resonance of the times is more than an emotional flashback.

Derek Taylor, the Beatles' publicist, acted as consultant to the Granada show and has since published a similarly titled book about the era. It's good reading, but there's something moving about seeing those times unfold on film. Maybe you had to be there -- but if you were, for these two hours at least, you can go home again.