The event kicked off on Thursday and will run through Sunday at Bethel Woods Center For The Arts.
Santana and the Doobie Brothers are scheduled to headline Saturday's lineup and John Fogerty is set to play Sunday.
More than 400,000 people attended the 1969 weekend event, which featured performances by Guthrie, Richie Havens, Sweetwater, Jimi Hendrix, Crosby Stills, Nash & Young, Joni Mitchell, Joan Baez, Santana, the Grateful Dead, Janis Joplin, Sly and the Family Stone, The Who, Sha Na Na and Jefferson Airplane.
"It was a great time," Billboard.com reported Guthrie told the press on Thursday. "For me, the Woodstock festival was a celebratory end of an era. It was not the beginning of anything. It was the end of something, and it was an end of a very turbulent time that was also very wonderful."
A separate, star-studded, anniversary event was scheduled to take place in Maryland this weekend, but was canceled in late July after permit issues and the loss of financial support led numerous music acts to back out.