Stills dropped out of the University of Florida to pursue a music career in the early 1960s. He played in a series of unsuccessful bands including The Continentals, which featured future Eagles guitarist Don Felder. Stills could also be heard singing solo in Gerde's Folk City, a well-known coffee house in Greenwich Village.
Stills eventually ended up in a nine-member vocal harmony group, the house act at the famous Cafe Au Go Go in NYC, called the Au Go Go Singers (Rick Geiger, Roy Michaels, Michael Scott, Jean Gurney, Kathy King, Nels Gustafson, Bob Harmelink, future bandmate in Buffalo Springfield Richie Furay & Stills). This group also did some touring in the Catskills and in the South, released one album in 1964, then broke up in 1965. Afterwards, Stills, along with four other former members of the Au Go Go Singers (Geiger, Michaels, Gurney & Scott) formed The Company, a folk/rock group. The Company embarked on a 6-week tour of Canada where Stills met a young guitarist named Neil Young. On the VH1 CSNY Legends special, Stills would say that Young was doing what he always wanted to do, "play folk music in a rock band." (This sentiment was repeated decades later; the shaky relationship has been well documented between the two, although they continued to perform together throughout various times in their lives.)
The Company broke up in New York within four months, opening up the way for Geiger to join a light opera company in Los Angeles; Michaels to link up with Jimi Hendrix, Gurney to go on to college while doing TV commercials, and Scott to tour with a retro-Highwaymen. Stills did session work and went to various auditions (including an unsuccessful attempt to become one of The Monkees). In 1966 he convinced a reluctant former Au Go Go Singer, Richie Furay, then living in Massachusetts, to move with him to California.
Stills, Furay, and Young reunited in Los Angeles and formed the core of Buffalo Springfield. Legend has it that Stills and Furay recognized Young's converted hearse on the streets of LA and flagged him down, a meeting described in the recent solo track "Round the Bend". The band would release three albums (Buffalo Springfield, Buffalo Springfield Again, and Last Time Around) and one hit single (Stills' "For What It's Worth") before disbanding.
Stills' guitar playing continually evolved. Early on, it displayed sources in generic rock and roll, blues, and country music, as well as the chordings familiar in the acoustic-folk music scene. Soon Stills' playing showed the influence of his friend Jimi Hendrix and also sometimes the rhythms and riffs of various kinds of Latin music. Stills is notorious for experimenting with the guitar itself. This includes such things as soaking strings in barbecue sauce or flipping pickups to mimic Hendrix playing a right-handed guitar left-handed. He is also known for using unconventional tunings, particularly when performing acoustically. He is also adept at piano, organ and bass and plays some drums. "Stephen had a vision", [Graham] Nash says. "David [Crosby] and I let him run with it". Stills played nearly every instrument on Crosby, Stills and Nash, earning the nickname Captain Manyhands from Rolling Stone.
During the disintegration of Buffalo Springfield, Stills joined up with ex-Byrd David Crosby and ex-Hollie Graham Nash to form the supergroup Crosby, Stills & Nash. Cass Elliot invited Graham Nash over to meet Stills and David Crosby at the home of well known folk musician and painter Joni Mitchell, who painted several artworks of the three. Mitchell also contributed the artwork seen on the cover of the CSNY collection album So Far, released in 1974. The cover photo pictured on the trio's first (self-titled) album in 1969 was taken on the back porch of a house in West Hollywood which was torn down the next day. Stills overdubbed much of the musical backing himself for the first Crosby, Stills, and Nash album with only Dallas Taylor's drums and some rhythm guitar from Crosby and Nash. Neil Young was added for their second album, and the group became Crosby, Stills, Nash, and Young. Despite several breakups and reformations, CSN (and sometimes CSNY) still record and tour to this day.
Having played at the Monterey Pop Festival with Buffalo Springfield, and both Woodstock and Altamont with CSNY, Stills performed at all three of the iconic rock festivals of the 1960s.
In the wake of CSNY's success, all four members recorded solo albums. In 1970, Stills released his eponymous album debut which featured guests Eric Clapton, Jimi Hendrix (on what was possibly his last recording before he died), "Mama" Cass Elliot, Booker T Jones and Ringo Starr (credited only as "Richie") as well as contributions from various members of the CSNY band. It provided Stills with the hit single "Love The One You're With" as well as the concert favorite "Black Queen." Stills followed this with Stephen Stills 2, which featured "Change Partners." Even though the song was written before CSN formed, Nash saw it as a metaphor for the many relationships in CSNY, while Stills viewed the band as something much less bland and repetitive.
The next year, Stills teamed up with ex-Byrd Chris Hillman and several CSNY sidemen to form the band Manassas. With Manassas Stills recorded the self-titled double album Manassas. The album was a mixture of blues, folk and Latin music divided into different sections, and is considered by many to be one of Stills' best albums.
During a Manassas tour in France, Stills met and married French singer-songwriter Veronique Sanson. Then he switched to Columbia Records, where he recorded two albums: Stills in 1975 and Illegal Stills, a pun on his name, in 1976. The former record found Stills in an uncharacteristically joyful mood; his marriage was going well, his son Chris had just been born, and he was happy living in Colorado. "To Mama From Christopher and the Old Man" was an exceptionally optimistic view of his new family.
In 1976, Stills attempted a reunion with Neil Young. At one point, Long May You Run was slated to be a CSNY record, but when Crosby and Nash left to fulfill recording and touring obligations, according to both David and Graham the other pair wiped their vocals from the recordings, as Stills and Young decided to go on without their erstwhile partners as The Stills-Young Band. However, Young would leave midway through the resulting tour due to an apparent throat infection. Stills was contractually bound to finish the tour, which he did, but upon returning home, his wife announced she wanted a divorce and wished to move back to France. Stills reunited with Crosby and Nash shortly afterwards, thanks to the efforts of Nash's future wife Susan, who got Nash to forgive Stills for wiping the Crosby and Nash vocals from Long May You Run. This led to the semi-permanent CSN reunion of 1977, which has persisted even though all three have released solo records since then.
In 1979 he travelled to Havana, Cuba, to participate in the Havana Jam festival that took place between March 2–4, alongside Weather Report, the CBS Jazz All-Stars, the Trio of Doom, Fania All-Stars, Billy Swan, Bonnie Bramlett, Mike Finnegan, Kris Kristofferson, Rita Coolidge and Billy Joel, plus an array of Cuban artists such as Irakere, with whom he toured the US after the Havana concerts. His performance is captured on Ernesto Juan Castellanos's documentary Havana Jam '79.
Although Crosby, Stills, Nash, and Young had difficulties with their differing individual goals, egos, and musical styles, in the early 1983 Daylight Again DVD from the 1982 CSN tour, Stills introduced the song, "Wasted on the Way", commenting that there were "three buddies who didn't know how to talk to one another for years"... finally 'making friends' getting rich, and it being good". According to Crosby's biography, it was his lowest point in his crack cocaine addiction which left him nearly bankrupt, in prison without funds for a time.
In 1997, Stills became the first person to be inducted into the Rock and Roll Hall of Fame twice in the same night for his work with CSN and the Buffalo Springfield. Fender guitars crafted a custom guitar and presented it to Stills to commemorate the occasion, this Fender Telecaster style guitar bears an inscription on the neck plate.
2005 saw Stills release Man Alive!, his first solo offering in 14 years. Man Alive! was released on the small English independent folk rock label Talking Elephant, and was not widely reviewed. The record did not chart on either side of the Atlantic, and was received lukewarmly the few critics who did review it.
Throughout 2006 and 2007, Stills toured regularly as a solo artist with "The Quartet", which consisted of drummer Joe Vitale, either Mike Finnegan or Todd Caldwell on keyboards, and either Kevin McCormick or Kenny Pasarelli on bass. Often a long acoustic solo section of the show would feature songs rarely played and showcase agile fingerstyle playing in standard and altered tunings. Stills toured Europe as a solo artist for the first time during October 2008.
Stills was a prolific songwriter before becoming a star performer; his composition "Sit Down, I Think I Love You" was a minor hit for The Mojo Men before it was recorded by Buffalo Springfield.
In 1966, Stills auditioned for The Monkees, but did not get the part, partially because his already-thinning hair and bad teeth made him look too old for the part, and partially because the actor contract required him to assign his music publishing rights to Screen Gems, something he did not want to do. Stills instead suggested to his former roommate, Peter Tork, that he audition; Tork got the job.
Stills was a close friend of Jimi Hendrix, who appears on Stills' eponymous first solo album. Reputedly, when Hendrix was forming his trio The Jimi Hendrix Experience, his manager contacted Stills' manager to invite Stills to become the group's bass player. Concerned that Stills' friendship with Hendrix and admiration for Hendrix' genius might prompt Stills to take the job rather than continue with the Buffalo Springfield, Stills' manager elected not to pass the message on to Stills. Noel Redding was then offered and took the job as bassist with the Experience. Within a year, both Stills and Hendrix were superstars in their own right; they continued to socialize and jam together informally until Hendrix' death in 1970.
Several of Stills' most notable songs, "Bluebird", "Suite: Judy Blue Eyes", "You Don't Have To Cry" and "Bluebird Revisited" were inspired by his intense on-again-off-again relationship with singer Judy Collins. In a 1971 interview in Rolling Stone Magazine the interviewer noted, "So many of your songs seem to be about Judy Collins". Stills replied, "Well, there are three things men can do with women: love them, suffer for them, or turn them into literature. I've had my share of success and failure at all three."
Stills' son, Justin Stills, was badly injured at age 26 snowboarding in Tahoe in 1997; an episode of Discovery Health's documentary series Trauma: Life in the ER featured his treatment and recovery. Another son, Henry, has been diagnosed with Asperger syndrome, and is profiled in the 2007 documentary Autism: The Musical. His son Chris and daughter Jennifer are both recording artists. His youngest son, Oliver Ragland, was born in 2004 and named in honor of Neil Young, whose maternal family name is Ragland.
On May 28, 2007, Stills sang the National Anthem for Game 1 of the 2007 Stanley Cup Finals between Anaheim and Ottawa in Anaheim, California.
On December 17, 2007, Graham Nash revealed on Larry King Live that Stills had been diagnosed with early stage prostate cancer and that his operation would take place on January 3, 2008, which is Stills' birthday. Stills said later in January 2008 that he had come through the operation with "flying colors."