Buffalo Springfield

Once they reached Los Angeles, Young and Palmer met up with Stephen Stills, Richie Furay, and Dewey Martin to form Buffalo Springfield. A mixture of folk, country, psychedelia, and rock, lent a hard edge by the twin lead guitars of Stills and Young, made Buffalo Springfield a critical success, and their first record Buffalo Springfield (1966) sold well after Stills' topical song "For What It's Worth" became a hit, aided by Young's melodic harmonics played on electric guitar. According to Rolling Stone, the Rock and Roll Hall of Fame and other sources, Buffalo Springfield helped create the genres of folk rock and country rock.

Distrust of their management, as well as the arrest and deportation of Palmer, exacerbated the already strained relations among the group members and led to Buffalo Springfield's demise. A second album, Buffalo Springfield Again, was released in late 1967, but two of Young's three contributions were solo tracks recorded apart from the rest of the group.

In many ways, these three songs on Buffalo Springfield Again, "Mr. Soul", "Expecting to Fly", and "Broken Arrow", are harbingers of much of Young's later work in that, although they all share deeply personal, almost idiosyncratic lyrics, they also present three very different musical approaches to the arrangement of what is essentially an original folk song. "Mr. Soul" is the only Young song of the three that all five members of the group performed together. In contrast, "Broken Arrow" was confessional folk-rock of a kind that would characterize much of the music that emerged from the singer-songwriter movement. Young's experimental production intersperses each verse with snippets of sound from other sources, including opening the song with a soundbite of Dewey Martin singing "Mr. Soul" and closing it with the thumping of a heartbeat. "Expecting to Fly" was a lushly produced ballad similar to the baroque pop of the mid-1960s, featuring a string arrangement that Young's co-producer for the track, Jack Nitzsche, would dub "symphonic pop".

In May 1968, the band split up for good, but to fulfill a contractual obligation, a final album, Last Time Around, was released, primarily from recordings made earlier that year. Young contributed the songs "On the Way Home" and "I Am a Child", singing lead on the latter. In 1997, the band was inducted into the Rock & Roll Hall of Fame; Young did not appear at the ceremony. The three surviving members, Furay, Stills and Young, appeared together as Buffalo Springfield at Young's annual Bridge School Benefit on October 23–24, 2010, and at Bonnaroo in the summer of 2011.