Steve Lacy was born Steven Norman Lackritz on July 23, 1934, in New York City. He picked up the soprano saxophone in his teens, and by sixteen was already sitting in with the Dixieland-revival crowd — veteran players decades his senior, among them trumpeter Henry "Red" Allen, clarinetist Pee Wee Russell, bassist George "Pops" Foster, and drummer Zutty Singleton, along with figures out of the Kansas City tradition like Buck Clayton, Dicky Wells, and Jimmy Rushing. The instrument itself was the tell: soprano sax had been almost entirely dormant in jazz since Sidney Bechet's prime, and it was Bechet's wide, singing vibrato and blues-rooted phrasing that had pulled the teenage Lacy toward the horn in the first place. He spent his earliest professional years playing old-time New Orleans repertoire before that traditionalist grounding gave way, with startling speed, to the avant-garde.

The turn came through pianist Cecil Taylor. Lacy joined Taylor's group in 1953, while still a teenager, and stayed through one of the most consequential apprenticeships in postwar jazz: he is on Taylor's 1956 debut Jazz Advance, one of the first fully realized statements of what would become free jazz, and he was in the band Taylor brought to the 1957 Newport Jazz Festival — an appearance now regarded as a landmark moment for the emerging avant-garde. Taylor's harmonic radicalism and rhythmic freedom gave Lacy a vocabulary that traditional soprano playing had no use for, and it set the direction — restless, structurally curious, unafraid of dissonance — that would define the rest of his career. Around the same period he also worked with arranger Gil Evans, appearing as a featured soloist on Gil Evans & Ten (1957), Great Jazz Standards (1959), and later the orchestrally ambitious The Individualism of Gil Evans (1964), sessions that put his soprano alongside Eric Dolphy and Wayne Shorter in Evans's dense, colorist arrangements.

The relationship that would outlast and eventually define all others began in 1958: Reflections (New Jazz/Prestige), the first album ever devoted entirely to the compositions of Thelonious Monk, recorded with pianist Mal Waldron, bassist Buell Neidlinger, and drummer Elvin Jones. Lacy went on to briefly join Monk's own working band in 1960, absorbing the music from inside its source, and from that point Monk's tunes never left his repertoire — they anchored virtually every album and performance he gave for the next four and a half decades, through dedicated solo-soprano recitals (Only Monk, 1987, recorded solo), quartet reunions, and sextet arrangements alike. Lacy became, by wide consensus, the most important interpreter of Monk's music after Monk himself, and in the process became the first genuinely avant-garde jazz musician to make the soprano saxophone his sole voice — reviving an instrument bebop had essentially discarded and establishing it, alongside Coltrane's later soprano work, as a legitimate modern jazz voice in its own right.

By the mid-1960s Lacy was pushing further outward. He co-led a quartet with trombonist Roswell Rudd built entirely around Monk's book — captured, years after the fact, on School Days (recorded live at a Manhattan coffee house in 1963, not issued until 1975 on Emanem) — and he began the itinerant, transatlantic period that would reshape his career. A 1965 trip to Copenhagen with pianist Kenny Drew was followed by a move to Rome, where he formed a quartet with South African expatriates Johnny Dyani (bass) and Louis Moholo (drums) alongside Italian trumpeter Enrico Rava; a 1966 concert by that group in Buenos Aires became The Forest and the Zoo (ESP-Disk, 1967), one of free jazz's starkest live documents. After a brief, difficult return to New York, Lacy relocated permanently to Paris in 1970. He cut Epistrophy — an all-Monk session for the French label BYG, recorded that same year with a European rhythm section — and settled into the city that would be his base for the next three decades, becoming, in the words of one obituary, "a widely respected figure on the European jazz scene, though he remained less well known in the United States" than his stature warranted.

Paris is also where Lacy built his most enduring vehicle: a sextet organized around his wife, the Swiss-born cellist, violinist, and vocalist Irene Aebi, alongside a rotating cast anchored for years by alto/soprano saxophonist Steve Potts, pianist Bobby Few, bassist Jean-Jacques Avenel, and drummer Oliver Johnson (later succeeded by John Betsch). The group's flexible instrumentation — expanding to larger ensembles or contracting to duos and solo recitals — let Lacy pursue an unusually literary, interdisciplinary strain of jazz: he set texts by poets Robert Creeley and Tom Raworth, by Samuel Beckett, by Beat collaborator Brion Gysin, by Herman Melville, by Bangladeshi poet Taslima Nasrin, and built extended works from the Tao Te Ching and Japanese haiku. Albums like The Way (recorded live in Basel, 1979; released 1980 on Hat Hut) and Momentum (1987, Novus/RCA) are characteristic documents of that sextet sound — through-composed, text-driven, and built for Aebi's voice as much as for Lacy's horn. He also became one of the pioneering figures of unaccompanied solo soprano saxophone performance, a discipline he shared with Sonny Rollins, Anthony Braxton, and Evan Parker, and he sustained an exceptionally prolific duo partnership with pianist Mal Waldron across more than two decades, alongside periodic reunions with Roswell Rudd — Trickles (1976), Regeneration (1983, with Han Bennink and Misha Mengelberg), and a final, Grammy-nominated studio reunion, Monk's Dream (recorded 1999, released 2000 on Verve). By any count, Lacy's discography as leader, co-leader, and featured collaborator runs into the hundreds of recordings — Discogs alone lists more than 700 entries under his name across original releases, live documents, and reissues.

Recognition followed the work rather than preceding it. In 1992 Lacy received a MacArthur Fellowship — the so-called "Genius Grant" — for a body of work built as much on visual art, poetry, and dance collaboration as on jazz itself. He won Down Beat's soprano saxophone poll repeatedly across his career. In 2002, after more than thirty years based in Europe, Lacy returned to the United States to teach at the New England Conservatory of Music in Boston. One of his last public performances came in March 2003, in front of roughly 25,000 people at a peace rally on Boston Common held shortly before the invasion of Iraq. He was diagnosed with liver cancer that August, and continued performing and teaching for months afterward. Steve Lacy died on June 4, 2004, at New England Baptist Hospital in Boston, at age 69, survived by Irene Aebi.

Lacy's style was built on a paradox he never fully resolved and never seemed to want to: a Bechet-derived, blues-rooted vocabulary learned in Dixieland bands, fused permanently with the harmonic and structural radicalism he absorbed as a teenager under Cecil Taylor. His decision to make soprano saxophone his only voice — at a moment the instrument had been almost entirely abandoned by modern players — forced him to build a personal language with almost no direct forebear to draw on beyond Bechet himself. Monk's compositions became the constant thread running through all of it: their angular intervals, their deliberate use of space, and their refusal of easy resolution matched something already present in Lacy's own melodic instincts, and his lifelong engagement with that book of tunes shaped how he thought about composition generally — spare, interval-conscious, alert to silence. The Paris years added a second dimension entirely: an interdisciplinary, text-and-image-driven approach to jazz composition, absorbed from two decades working alongside poets, visual artists, and choreographers, that had few real counterparts among his American contemporaries.