When the red light went on at Hollywood's Capitol Studios in 1967, singer Linda Ronstadt was scared. There to record "Different Drum"—her first lead-vocal single as a member of the Stone Poneys—Ms. Ronstadt was expecting to sing an acoustic ballad version of the song accompanied by her two bandmates.

Linda Ronstadt (shown in 1968) was caught off guard in the studio when confronted with new musicians and a faster arrangement. Henry Diltz/Corbis

Instead, a new faster arrangement had been written, a rhythm section and string players were brought in to replace the other two Stone Poneys, and Ms. Ronstadt had just seconds to figure out how she was going to phrase the lyrics and make the song work.

Released in September 1967, the single—written by future-Monkee Michael Nesmith —peaked at No. 13 on Billboard's pop chart, launching Ms. Ronstadt's career and ushering in a new solo female folk-rock era. Ms. Ronstadt, 67, author of "Simple Dreams: A Musical Memoir," published in September; Mr. Nesmith, 70; harpsichordist Don Randi, 76, and Stone Poney Bobby Kimmel, 73, talked about the song's evolution. Edited from interviews:

Michael Nesmith, who wrote the song pre-Monkees. Michael Ochs Archives/Getty Images

Michael Nesmith: In 1964 I had been playing guitar in folk and bluegrass bands and wanted to sing solo. So I began writing songs. I wrote "Different Drum" early one morning on the back porch of my San Fernando Valley apartment. The lyrics, about a breakup, came fast—but they had nothing to do with my personal life. I was newly married with a pregnant wife.

Whenever I wrote, I liked creating little 'movies of the mind.' I was thinking about two lovers—one of whom decides they love different things. In later years, comedian Whitney Brown referred to "Different Drum" as the first "it's not you, it's me" breakup song.

In 1965 I met John Herald of the Greenbriar Boys trio. We sat down and began sharing songs. John loved "Different Drum" and slowed it down when he recorded it the following year for Vanguard Records.

Linda Ronstadt: I moved from Tucson, Ariz., to Los Angeles in 1965 to sing with Bobby Kimmel and Kenny Edwards. There were plenty of gigs at folk clubs then. Kenny played a Gibson mandolin, Bobby played a Martin guitar and I sang harmonies.

Naming our folk trio the Stone Poneys was Kenny's idea. He got the name from Charley Patton's song "Stone Pony Blues." In those days, the word "stone" also meant "heavy, man." Bobby was writing most of the songs then—but for his voice and range. At some point in late '66, I wanted a song that suited my voice so I could sing lead.

That's when I heard the Greenbriar Boys' single "Different Drum." I knew it could be a hit for us. In 1967, our producer at Capitol, Nik Venet, set up a recording session. It was at Capitol's Studio B, where Frank Sinatra recorded. The plan was to record three songs in three hours that day.

I thought we were going to record an acoustic ballad version of "Different Drum" with Bobby and Kenny. But when I walked into the studio, there were other musicians there I didn't know. Bobby and Kenny played on two of the songs, but on "Different Drum," Nik asked them to sit out.

Bobby Kimmel: Kenny and I didn't mind. It was always going to be a solo vocal feature for Linda anyway, and Nik wanted more going on instrumentally behind her. Kenny and I stood in the engineer's booth and watched and listened.

Ms. Ronstadt: At first, I wasn't happy. I thought we'd have a better shot on the radio with an acoustic version, since groups like Peter, Paul and Mary were having hits. But Nik insisted. He said he had asked Jimmy Bond to write an arrangement and brought in Don Randi to play harpsichord, Al Viola on guitar and Jimmy Gordon on drums. Bond played bass, and Sid Sharp arranged and conducted a string section. They were all there.

We didn't rehearse. I was just thrown into it. I was completely confused. I didn't have the lyrics in front of me—I sang them from memory. Since I can't read music, I didn't have a lead sheet either. I knew I could remember the words, but I wasn't sure how to phrase them with the new arrangement and faster tempo.

Different instruments pull different textures out of my voice, which was conditioned to sing with guitar and mandolin. The harpsichord and strings were going to be harder. We recorded the second take without any overdubbing. That became the version you hear on the record.

Don Randi: Jimmy Bond had me play a double-keyboard harpsichord that day, to give the song a psychedelic-pop feel. I only had the chord changes and made up the rest on the spot, including the solo. I had been trained as a classical pianist, so giving it a classical feel wasn't a problem.

By '67, I had recorded as part of L.A.'s Wrecking Crew studio band on hundreds of rock recordings, including sessions with the Beach Boys and Phil Spector. This was a nice change-up. Nik knew his stuff and went to bat for Linda with us before she came in, Nik told me, "Wait until you hear this girl sing. You won't believe it."

He was right. She had this innocence and humility that won me over. If she had been frightened, you'd never have known it. Linda was so down-to-earth and natural—she even recorded that song barefoot.

Bands Who Were Hip to the Harp

The Doors posed in Germany in 1968. The group featured the harpsichord on "Love Me Two Times" in 1967. Redferns

Ms. Ronstadt: I first heard the single when the band's car broke down in September '67. Soon after we pushed it into a gas station, I heard the guitar-harpsichord intro faintly coming from a radio in back of the garage. The mechanics had it tuned to KRLA—L.A.'s Top-40 AM station. I was stunned.

Mr. Nesmith: I first heard Linda's record on the radio in Philadelphia, while riding in a limo with the Monkees. No one in the car believed I had written the song. Linda did more for that song than the Greenbriar Boys' version. She infused it with a different level of passion and sensuality. Coming from the perspective of a woman instead of a guy, the song had a new context. You sensed Linda had personally experienced the lyrics—that she needed to be free.

Mr. Kimmel: The irony, of course, is I didn't sing or play on my group's biggest hit. But you know what? It wouldn't have mattered even if I had. It was Linda's time.

Ms. Ronstadt: I'll be honest—I was never happy with how I sounded. It took me 10 years to learn how to sing before I had skill and craft. Today I will break my finger trying to get that record off when it's on. Art wasn't meant to be frozen in time like that.

Everyone hears something in that song—a breakup, the antiwar movement, women's lib. I hear fear and a lack of confidence on my part. It all happened so fast that day.