BOSTON—The telltale clues at this weekend's festivities, 40 years late, included the tie-dye T-shirt on a woman who also wore a peace symbol necklace and a garland in her hair (”;I thought everyone would be dressed like this,”; she said).

When the group stood for its class picture, even those in suits and ties made the peace sign. Others raised clenched fists.

And one of them marched in the commencement processional with an anti-war poster slung around his neck.

The accouterment and spirit of their era still radiate from the class of 1970, despite the harsh and abrupt ending to their years at Boston University.

That spring was supposed to bring a flowery conclusion to their four years of academe. But President Richard M. Nixon had invaded Cambodia. National Guardsmen had gunned down students at Kent State, killing four and wounding nine. Young men still faced the draft. And this campus, like many across the country, was in turmoil, with strikes, sit-ins, building takeovers and firebombings.

The situation became so incendiary that, for safety's sake, university officials called off final exams, canceled graduation and sent students packing.

This weekend, on what would have been the 40th anniversary of that ceremony, the university sought to make amends with a proper graduation.

But more than pomp and circumstance, the university wanted to give the students—now in their early 60s, many of them grandparents—a chance to heal the wounds, reflect on what their time here had meant and feel better about their alma mater.

“;This is not an apology,”; Robert A. Brown, the president of the university, said in an interview beforehand. “;We did exactly the right thing by calling off exams. It's an opportunity to reach out to this cadre of alums and say, 'Come, be with us.”;'

About 300 of the 3,000-member class showed up, many with their grown children in tow, not to mention unfinished business.

“;That was a big deal,”; Dr. Marcia Wells Avery, one of three black nursing students in the class of 1970, said of her canceled graduation. “;It was worse for the parents and the grandparents, many of whom are dead now and were robbed of that opportunity to see their child march across that stage.”;

“;My father vowed that BU would never get a penny from him,”; added Avery, who is now a nursing professor at Northwestern State University in Louisiana.

Still, Avery was enjoying the weekend. She decided to drop by the bookstore and “;buy up all the BU paraphernalia”; she could find. She said she would even consider making a future donation to the school.

And by the end of the ceremonies on Sunday, she was beaming. “;It's OK,”; she said. “;I feel complete.”;

Although officials avoided any mention of fundraising during the weekend, many class members assumed that this was one of the university's long-term goals as it sought to strengthen its bonds with this class, many of them professionals, many on the verge of retirement.

Scott Nichols, the university's chief fundraiser, said that “;there is no plan afterward to swoop in.”; However, he added: “;These students had this strange moment in time. Why not treat them nicely? In a fundraising sense, you never go wrong treating people nicely and there's always payback, but we have no solicitation strategy.”;

On Saturday the class began trickling back to the urban campus. The ice-breaking social event was an extensive slide show of photographs taken by Peter Simon, a member of the class and brother of Carly Simon.

“;Forty years ago I probably never would have gone to graduation because I was such a hippie,”; Simon said to chuckles and applause. But now, he said, “;time has mellowed me.”;

Simon said that when he speaks about his photography around the country, students frequently say to him, “;God, I wish I'd been alive and been part of your generation because it's really boring now.”; He said he responds by saying: “;But you have all this texting! You have cell phones!”;

“;And they say they'd give all that stuff away for the kind of experiences we had,”; he said. “;And I have to say, I agree.”;

Many of those who came said some classmates had no interest in attending. “;They felt like what's done is done and it has no relevance to their lives anymore,”; said Amy Weiner Nathans, a retired foreign language teacher who lives in Ohio.

But many came just for the fun of it. George Watson, who is now chairman of the foreign language department at a local high school, said he came back “;to rekindle that passion that I felt back then.”;

Kit Coffey, who worked in medical sales and lives on Boston's South Shore, said she came because she thought it would be “;a hoot”; to remember her origins as a rebellious college student.

“;How did I become a suburban housewife?”; she asked. This era, she said, “;is hard to explain to people, then you forget about it because you're in your everyday life. And then you look back at this time and think, wow, what was that all about?”;

This would not be a gathering of baby boomers without elaborate attention paid to the music. As the class moved quietly to the pews of Marsh Chapel for a Service of Remembrance, a pianist played the soundtrack of their era: “;Fire and Rain,”; “;The Long and Winding Road”; and “;Both Sides Now.”; A soloist, backed by an acoustic guitar, sang “;Bridge Over Troubled Water.”;

From the lectern, James Carroll, who was the Catholic chaplain of the university at the time, vividly recalled the vigil here for Kent State students, when American soldiers, dressed in combat gear and carrying rifles, encircled the students at a sit-in. “;The real meaning of that trauma sank in,”; he said of Kent State. “;Our government, having killed legions of Vietnamese, was now prepared to kill you. Us.”;

The soloist led the class in singing “;Let It Be,”; during which many wiped away tears.

That sharp emotional reminiscence over, the events of the weekend took a more joyful turn.

At their own convocation on Sunday morning, class members—with their gray hair tucked under their caps and lifetimes of experience under their belts—strode across the stage in their fire-engine-red gowns and received their diplomas (actually, certificates, since their real diplomas had been mailed to them at the time).

Swaying back and forth, they spontaneously sang “;All we are saying, is give peace a chance.”; They bopped and shimmied off the stage to “;Ain't No Mountain High Enough.”;

In the afternoon, they were given pride of place among 25,000 other graduates, family and friends at the sun-splashed commencement ceremonies on Nickerson Field. Younger graduates cheered them on. Several speakers paid them homage as the big video screens featured photos of their demonstrations, their love-ins and their long hair.

And the commencement speaker, Attorney General Eric Holder, singled them out.

“;I love you all,”; he told the crowd. But gesturing to the class of 1970, sitting right in front of him, he said, “;But these are my people.”;

For a day, at least, the establishment was honoring them, a turnabout from 40 years ago.