“I really had a great time.,” Dominis told LIFE.com, decades after the fact. “I was much older than those kids, but I felt like I was their age. They smiled at me, offered me pot. . . . You didn’t expect to see a bunch of kids so nice; you’d think they’d be uninviting to an older person. But no—they were just great!

Large crowd of people, incl. people sitting on top of cars & busses, during the Woodstock Music & Art Fair.

Long haired man seated on top of a treehouse-like platform playing the guitar, during the Woodstock Music & Art Fair.

Paraphernalia stand in the woods featuring pillows, posters, & incense during the Woodstock Music & Art Fair.

Several youths washing their feet at a water pump during the Woodstock Music & Art Fair.

Unident. man seated w. two young boys in front of a wildly painted schoolbus, during the Woodstock Music Art Fest.

Several youths huddled together under a piece of clear plastic in the rain during the Woodstock Music & Art Fair.

Night overview of the stage all lit up during unident. performance, at the Woodstock Music & Art Fair.

Long exposure of huge night time crowd, showing lights all over, during the Woodstock Music & Art Fair.

Two unident. women giving medical care to unident. men, during the Woodstock Music & Art Fair.

Young people standing in the mud & water talking, during the Woodstock Music & Art Fair.

Jackie Barg sitting on the ground & blowing bubbles, during the Woodstock Music & Art Fair.

Several young people dish out food to youths in food line during the Woodstock Music & Art Fair.

Wide-angle overall of huge crowd facing the distant stage, during the Woodstock Music & Art Fair.

Several young people dishing out food to youths in food line, during the Woodstock Music & Art Fair.

Young people camping out w. tents in the midst of a cemetery, during the Woodstock Music & Art Fair.

Several youths huddled together under a piece of clear plastic in the rain during the Woodstock Music & Art Fair.

Overall of crowds of young people milling around big yellow tents during the Woodstock Music & Art Fair.

Group of people writing, typing & talking on the phone, prob. reporters, during the Woodstock Music & Art Fair.

Several young people dish out food to youths in food line during the Woodstock Music & Art Fair.

Hippie couple standing barefoot on a road holding a bundle & wine bottle during the Woodstock Music & Art Fair.

Young people camping out w. tents on a grassy hillside, during the Woodstock Music & Art Fair.

Hippie couple posed together arm in arm w. others around them, during the Woodstock Music & Art Fair.

Several young people dish out food to youths in food line, during the Woodstock Music & Art Fair.

Several youths huddled under a green tarp, during the Woodstock Music & Art Fair.

Wide-angle overall of huge crowd facing the distant stage, during the Woodstock Music & Art Fair.

Overall of the huge crowd, during the Woodstock Music & Art Fair.

Overall of the huge crowd, looking towards the large yellow tents, during the Woodstock Music & Art Fair.

Overall of the huge crowd, looking towards the large yellow tents, during the Woodstock Music & Art Fair.

Couple twisting a blanket between them, prob. trying to squeeze out the water, during the Woodstock Music & Art Fair.

Young couple, seen from the back, kissing at night.

Overall of the huge crowd & the stage, looking to the tent camping area beyond, during the Woodstock Music & Art Fair.

Chuck Morgan (L) sitting in the mud & water w. a friend, during Woodstock Music & Art Fair.

Several young people holding plastic containers attempt to get water, during the Woodstock Music & Art Fair.

Kathy O'Brien wearing a bathing suit and washing her hair w. a bar of soap at a water pump, during the Woodstock Music & Art Fair.

Hippie girl climbing a lashed structure and looking at baby chicks in a coop, during the Woodstock Music & Art Fair.

Several young people standing at water pump attempting to get water, during the Woodstock Music & Art Festival.

Several youths, both dressed & in the nude, washing in a lake during the Woodstock Music & Art Fair.

Overall of crowds of young people milling around big yellow tents during the Woodstock Music & Art Fair.

Group of hippies hanging out at a playground, during the Woodstock Music & Art Fair.

The original plan was for an outdoor rock festival, “three days of peace and music” in the Catskill village of Woodstock. What the young promoters got was the third largest city in New York state, population 400,000 (give or take 100,000), location Max Yasgur’s dairy farm near the town of White Lake.One of thephotographers on scene during the festival, John Dominis, summed up his own recollections of Woodstock this way:Here is a gallery of pictures—many of which previously unseen—from those heady, rain-soaked days and nights.(Photos by John Dominis, via LIFE archives