During the mid-1960s, he wrote, performed, and produced many Billboard Top 20 hits for artists such as Barry McGuire, the Searchers, Jan and Dean, Herman's Hermits, Johnny Rivers, the Grass Roots, the Turtles, and the Mamas and the Papas.

Their partnership yielded two US Top Ten hits—Herman's Hermits' "A Must to Avoid" (1965) and Johnny Rivers' "Secret Agent Man" (1966)—and the Turtles' "You Baby" (1966).

[3] There, he formed a partnership with Steve Barri,[4] and the duo made several attempts at recording a hit single under names such as Philip and Stephan, The Rally-Packs, The Wildcats, The Street Cleaners, Themes Inc., and The Lifeguards.

In 1963, they came to the attention of Screen Gems executive Lou Adler, who decided to use them as backing singers and musicians (Sloan on lead guitar and Barri on percussion) for Jan and Dean, whom he managed.

Jan Berry used Sloan as the lead falsetto voice instead of Dean Torrence on the band's top 10 hit "The Little Old Lady from Pasadena".

Billboard Top 100 hit, "Kick That Little Foot Sally Ann", arranged by Jack Nitzsche and performed by a Watts, California-born artist named Round Robin.

Due to its line "You're old enough to kill, but not for votin'", "Eve of Destruction" was used as a rallying cry by supporters of the Twenty-sixth Amendment to the United States Constitution, which changed the voting age from 21 to 18 as of 1971.

[5] Sloan also became a session guitarist as part of the group of L.A. session musicians known as The Wrecking Crew, working with such well-known backing musicians as drummer Hal Blaine, guitarist Tommy Tedesco, bassists Joe Osborn and Carol Kaye, and bassist/keyboardist Larry Knechtel, among others.

While working with Barry McGuire, Sloan created and played a guitar introduction as a hook to a new song by John Phillips entitled "California Dreamin'", and the same backing track was used for the hit version by Phillips' group The Mamas & the Papas, which led to Sloan being a regular in their recording sessions.

[6] Sloan generally played the lead guitar tracks on most of the songs he wrote, including the famous riff in "Secret Agent Man".

His single "Sins of a Family" reached the Billboard top 100 in fall 1965, in the wake of the huge success of "Eve of Destruction".

They also produced a number of other acts, from Ann-Margret to The Robbs to Canadians Terry Black and Patrician-Anne McKinnon (both of whom had hits in Canada with Sloan-Barri songs) to Dunhill acts such as Shelley Fabares, The Ginger Snaps featuring Dandee Duncan, The Thomas Group (headed by Danny Thomas's son Tony), and The Iguanas (a Mexican band that did not speak English).

As a favor to a friend, Sloan in 1968 first met the relatively unknown Jimmy Webb at a private home for an informal but eye-opening visit.

"[1] During the Summer of Love, Sloan played as a solo artist on the first day (Saturday June 10, 1967) of the Fantasy Fair and Magic Mountain Music Festival.

In 1969, Sloan's "New Design" was included on the Ruby, Don't Take Your Love To Town album by Kenny Rogers and The First Edition.

He repeatedly reported that Dunhill made threatening advances to force him to sign away the rights to his valuable compositions and that the reason for his absence from the music scene was to battle illnesses.

He finally found relief from his long illness with help from Indian guru Sathya Sai Baba.

Guests included Frank Black, Buddy Miller, Lucinda Williams, Felix Cavaliere, Tom Petersson and Gary Tallent.

These recordings began when Sloan attended a concert in Los Angeles, featuring Beethoven compositions, that affected him deeply.

This last musical project led to him forgiving his transgressors, leaving his anger behind him and moving forward with peace, love and serenity for the remainder of his life.

In 2008, UK-based Big Beat label did a near-definitive reissue of Sloan's solo recordings for Dunhill.

Entitled Here's Where I Belong: The Best of the Dunhill Years 1965–1967, the CD omits the album tracks "When the Wind Changes" and "Patterns Seg.

4", while Sloan's final Dunhill recording, "I Can't Help But Wonder, Elizabeth", made its legal CD debut on this release.

In 2012 it was covered by the British singer Rumer, who treated it as the signature song on her Boys Don't Cry album.