Gary Ronald McFarland was born October 23, 1933, in Los Angeles, California, and moved with his family to Grants Pass, Oregon, at fifteen. He discovered jazz there through records by Miles Davis, Lester Young, and Woody Herman, but he came to music late and almost sideways: while serving in the Army he grew interested in jazz and tried, without much success, to play trumpet, trombone, and piano. He didn't pick up the vibraphone — the instrument he'd become known for — until 1955, and by his own account he was self-taught on it and as a composer-arranger. A chance 1957 encounter with a guitarist named Santiago Gonzales, who encouraged his melodic instincts, pushed him to teach himself music notation from scratch.

That unconventional path led, improbably, to a scholarship at the Lenox School of Jazz in 1959 and a single semester at the Berklee School of Music the same year, where he wrote for Herb Pomeroy's big band and came under the wing of pianist John Lewis. Lewis steered him away from performance and toward large-ensemble arranging — advice that shaped the rest of his career. Because McFarland never went through conventional conservatory training, his orchestration developed without the usual guardrails; the jazz educator Rayburn Wright later identified his signature move as the "grind," layered major and minor seconds that thickened Duke Ellington's harmonic language into something distinctly McFarland's own.

The break came in 1961, when valve trombonist Bob Brookmeyer heard two of McFarland's compositions, "Weep" and "Chuggin'," and championed them to Gerry Mulligan for the Concert Jazz Band. Mulligan recorded them for Gerry Mulligan Presents a Concert in Jazz (1961, Verve) and Gerry Mulligan '63, and the connection opened doors fast: that same year McFarland arranged Bob Brookmeyer's own Gloomy Sunday and Other Bright Moments and worked on Johnny Hodges' Blue Hodge. Producer Creed Taylor at Verve became his most important patron, giving McFarland's name equal billing as "The Gary McFarland Orchestra" on Anita O'Day's All the Sad Young Men (1962) and on his first outing as a billed leader, The Jazz Version of "How to Succeed in Business Without Really Trying" (1962) — an inventive reworking of the Frank Loesser Broadway score featuring an all-star lineup that included Phil Woods, Clark Terry, Doc Severinsen, Jim Hall, Kenny Burrell, and Hank Jones.

1962 also brought the record most people still associate with his name: fresh off the success of Jazz Samba, Stan Getz asked the 28-year-old McFarland to arrange and conduct a big-band bossa nova session. Big Band Bossa Nova, produced by Taylor and recorded at CBS's 30th Street Studio, became one of the defining records of the bossa nova boom and cemented McFarland's reputation as an arranger who could handle Brazilian idiom inside a jazz big-band frame without flattening either. The following January he recorded what many critics still consider his most significant work as a leader: The Gary McFarland Orchestra Featuring Special Guest Soloist: Bill Evans (1963, Verve), six original compositions scored for an eleven-piece chamber ensemble with two violas and two cellos, built around Evans's piano and featuring Jim Hall on guitar and Phil Woods on clarinet — described by one biographer as sublime, evocative music built from deceptive simplicity.

By the mid-1960s McFarland was pulling in two directions at once. He assembled a touring small group featuring the young guitarist Gábor Szabó and reedman Sadao Watanabe, heard on The In Sound (1965), while also chasing commercial crossover with Soft Samba (1965), a collection of pop and bossa covers that sold well but was savaged by critics — DownBeat gave it one star and called it "cheap and trivial... musical self-pollution," and Melody Maker named it the least memorable record of the year. McFarland didn't flinch from the tension; Soft Samba Strings (1967) doubled down on the string-laden pop-jazz sound, while Profiles (1966), a live big-band date recorded at Lincoln Center's Philharmonic Hall with Clark Terry, Bob Brookmeyer, Zoot Sims, and Szabó, and The October Suite (1967) — six through-composed movements written for pianist Steve Kuhn, with Ron Carter on bass — pushed in the opposite direction, toward a more ambitious, classically inflected jazz. McFarland also recorded two duo/co-billed records with Szabó in 1966: Simpático, trading originals and unlikely covers of the Beatles' "Norwegian Wood" and "The Word," and Gypsy '66, billed to "Gábor Szabó with Gary McFarland & Co.," on which McFarland played marimba and handled the arrangements rather than leading outright. He also scored the 1966 MGM thriller Eye of the Devil, starring David Niven and Deborah Kerr, though the soundtrack went unreleased commercially until a 2008 limited pressing.

In 1968 McFarland co-founded Skye Records with music executive Norman Schwartz, Szabó, and vibraphonist Cal Tjader — a label pitched, per a Billboard report at the time, at "established artists who are unhappy with their present record company affiliation." McFarland served as one of its principal creative forces, arranging and producing for other Skye artists (including Lena Horne and Szabó's Lena & Gabor) in addition to his own Does the Sun Really Shine on the Moon? (1968), the ambitious orchestral suite America the Beautiful (An Account of Its Disappearance) (1969) — scored for a huge ensemble including Randy Brecker, Hubert Laws, and Joe Farrell — and Today (1970), featuring Ron Carter on bass and Airto Moreira on percussion. Skye lasted less than two years and folded into bankruptcy in 1970 after roughly twenty-one releases. McFarland spent his last year pursuing Broadway and film work, scoring the 1971 film Who Killed Mary What's 'Er Name?, and recorded Butterscotch Rum (1971, Buddah), a sunshine-pop vocal collaboration with lyricist and political cartoonist Peter Smith.

McFarland never got the chance to build on any of it. On the afternoon of November 2, 1971, he was at Bar 55 on Christopher Street in Greenwich Village with two friends, drummer Gene Gammage and writer David Burnett, when liquid methadone was mixed into their drinks. McFarland went into cardiac arrest and died; Burnett fell into a coma and died several days later; Gammage survived but never publicly discussed what happened. No police investigation was conducted, and whether the poisoning was accidental or deliberate has never been established. McFarland was 38. He was survived by his wife, Gail Evelyn Frankel, whom he married in 1963, and their children Milo and Kerry. A posthumous compilation, Requiem for Gary McFarland, appeared on Cobblestone Records in 1972. His reputation dimmed for decades after his death, overshadowed by the commercial projects of his final years, but musicians never entirely forgot him: Brookmeyer said McFarland "didn't know enough to be like anybody else," and in 2002 the Mark Masters Ensemble recorded previously unheard McFarland compositions on the tribute album Wish Me Well. A 2014 documentary, This Is Gary McFarland, revived interest in his catalog further.

McFarland cited Duke Ellington, Billy Strayhorn, Gil Evans, and Miles Davis as his primary influences, and his arranging vocabulary shows all four: Ellington and Strayhorn's harmonic density (extended, per Rayburn Wright, through McFarland's own "grinds" of stacked major and minor seconds), Gil Evans's textural patience, and a Davis-like preference for space over clutter. Because he came to orchestration self-taught rather than through conservatory training, his writing avoided the reflexive habits of formally schooled arrangers — Steve Kuhn noted that his string and woodwind writing succeeded "despite limited formal training in scoring," built instead around an instinct for what specific musicians did well and a willingness to let an ensemble breathe rather than filling every bar. That same restlessness kept him moving between idioms most arrangers would have picked one lane within: big-band bossa nova, chamber-scored modern jazz, live all-star big-band writing, and unabashedly commercial vocal pop, sometimes within the same eighteen-month stretch. It made him hard to pin down critically in his lifetime, and it's a big reason he's remembered today as much for individual records — Big Band Bossa Nova, the Bill Evans collaboration, The October Suite — as for a single consistent style.