The Eagles, Jackson Browne and Linda Ronstadt were three of the most important musical acts of the 1970s, and they join musical forces for a spectacular live performance in classic archival footage that has turned up online.

In the clip below, the iconic '70s superstars all take the stage together for a stellar rendition of the Eagles' debut single, "Take It Easy," that features Browne and Ronstadt both on acoustic guitars and backing vocals. As one YouTube viewer comments, "You know you've hit the big time when your back up singers are Jackson Browne and Linda Ronstadt."

The footage appears to derive from the same television appearance the Eagles made on Don Kirshner's Rock Concert, where they also backed Ronstadt on her hit "Silver Threads and Golden Needles."

Both Ronstadt and Browne had extensive ties to the Eagles; he and singer-guitarist Glenn Frey co-wrote "Take It Easy" when they were neighbors in the years before either one had scored any success, and the original lineup of the Eagles first met when Ronstadt hired them as a group of country-rock "all-stars" for her Silk Purse Tour in 1971.

They made their live debut with her during a performance at Disneyland on July 12, 1971, which wound up being the only concert they ever played with her. The chemistry between them was so apparent that they broke away to form the Eagles after that, leaving Ronstadt to hire an entirely new slate of musicians.

Ronstadt went on to record her own solo rendition of "Desperado," and Eagles drummer and singer Don Henley also provided harmony vocals on her recording of Roy Orbison's "Blue Bayou" in 1977. Browne also recorded his own version of "Take It Easy" for his sophomore album, For Everyman, in 1973. His rendition of the song did not chart when he released it as a single.

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