The Grass Roots was originated by the writer/producer team of P.F. Sloan and Steve Barri as a pseudonym under which they would release a body of Byrds/Beau Brummels-style folk-rock. Sloan and Barri were contracted songwriters for Trousdale Music, the publishing arm of Dunhill Records, which wanted to cash in on the folk-rock boom of 1965. Dunhill asked Sloan and Barri to come up with this material, and a group alias under which they would release it. The resulting "Grass Roots" debut song, "Where Were You When I Needed You," sung by Sloan, was sent to a Los Angeles radio station, which began playing it. The problem was, there was no "Grass Roots." The next step was to recruit a band that could become the Grass Roots. Sloan found a San Francisco group called the Bedouins that seemed promising on the basis of their lead singer, Bill Fulton. Fulton recorded a new vocal over the backing tracks laid down for the P.F. Sloan version of the song. The Bedouins were, at first, content to put their future in the hands of Sloan and Barri as producers, despite the fact that the group was more blues-oriented than folk-rock. However, the rest of the group was offended when Fulton was told to record their debut single, a cover of Bob Dylan's "The Ballad of a Thin Man," backed by studio musicians. When that single, released in October of 1965, became only a modest hit, the Bedouins -- except for their drummer, Joel Larson -- departed for San Francisco, to re-form as the Unquenchable Thirst. Sloan and Barri continued to record. "Where Were You When I Needed You" was released in mid-'66 and peaked at number 28, but the album of the same name never charted.

Amid the machinations behind Where Were You When I Needed You, no "real" Grass Roots band existed in 1966. A possible solution came along when a Los Angeles band called the 13th Floor submitted a demo tape to Dunhill. This group, consisting of Warren Entner (vocals, guitar, keyboards), Creed Bratton (lead guitar), Rob Grill (vocals, bass), and Rick Coonce (drums), was recruited and offered the choice of recording under their own name, or to take over the name the Grass Roots, put themselves in the hands of Sloan and Barri, and take advantage of the Grass Roots' track record. They chose the latter, with Rob Grill as primary lead vocalist. The first track cut by the new Grass Roots in the spring of 1967 was "Let's Live for Today," a new version of a song that had been an Italian hit, in a lighter, more up-tempo version, for a band called the Rokes. "Let's Live for Today" was an achingly beautiful, dramatic, and serious single and it shot into the Top Ten upon its release in the summer of 1967. An accompanying album, Let's Live for Today, only reached number 75. The group began spreading its wings in the studio with their next album, Feelings, recorded late in 1967, which emphasized the band's material over Sloan and Barri's. This was intended as their own statement of who they were, but it lacked the commercial appeal of anything on Let's Live for Today, sold poorly, and never yielded any hit singles. Eleven months went by before the group had another chart entry, and during that period, Sloan and Barri's partnership broke up, with Sloan departing for New York and an attempt at a performing career of his own. The band even considered splitting up as all of this was happening. The Grass Roots' return to the charts (with Barri producing), however, was a triumphant one -- in the late fall of 1968, "Midnight Confessions" reached number five on the charts and earned a gold record. "Midnight Confessions" showed the strong influence of Motown, and the R&B flavor of the song stuck with Barri and the band.

In April of 1969, Creed Bratton left the band, to be replaced by Denny Provisor on keyboards and Terry Furlong on lead guitar. Now a quintet, the Grass Roots went on cutting records without breaking stride, enjoying a string of Top 40 hits that ran into the early '70s, peaking with "Temptation Eyes" at number 15 in the summer of 1971. Coonce and Provisor left at the end of 1971, to be replaced by Reed Kailing on lead guitar, Virgil Webber on keyboards, and Joel Larson -- of the original Bedouins/Grass Roots outfit -- on drums. They arrived just in time to take advantage of the number 16 success of "Two Divided by Love," which was the last of the Grass Roots' big hits. The Grass Roots soldiered on for a few more years, reaching the Top 40 a couple of times in 1972, but their commercial success slowly slipped away during 1973. They kept working for a few more years, but called it quits in 1975. Rob Grill remained in the music business on the organizing side, and by 1980 was persuaded by his friend John McVie to cut a solo album, Uprooted, which featured contributions by Mick Fleetwood and Lindsay Buckingham. By 1982, amid the burgeoning oldies concert circuit and the respect beginning to be accorded the Grass Roots, Grill formed a new Grass Roots -- sometimes billed as Rob Grill and the Grass Roots -- and began performing as many as 100 shows a year. Their presence on various oldies package tours saw to it that the Grass Roots' name remained visible. Grill continued performing with later incarnations of the band into the 2000s; however, he endured the pain of degenerative bone disease for years and in June 2011 suffered a head injury. The following month Grill died in Tavares, Florida of complications from that injury at the age of 67.