Performers on early Monkees recordings included Glen Campbell (lead guitar on "Mary, Mary"), Hal Blaine (drums), Carole King (keyboards, backing vocals), Louie Shelton (lead guitar), Tommy Boyce and Bobby Hart (guitars, keyboards, backing vocals), Neil Diamond (backing vocals). Michael Nesmith was allowed to write and produce two songs per album, but wasn't allowed to play - and his songs weren't used on singles, even as the B-side.
With the dual demands that they perform in public, and prove themselves as recording artists, the stars of the TV show began rehearsing nights and weekends. Gradually they could carry out a full set of songs, well enough for a Sixties pop concert, and began demanding a second chance to play on their own records. (It was never the Monkees' intention to fully replace the Kirshner-headed team of musicians and producers; they simply wanted a role in the recordings that would satisfy them, and their fans and critics.) Nesmith also wanted a share of the Monkees singles; knowing that royalties for B-sides were paid the same as A-sides, he reasoned even the B-side of a single would be worth something. (As did his competing writers and producers, and their boss.)
Early studio tryouts weren't considered good enough to release, and with both heavy filming and appearance (mostly as comedians, not as musicians) schedules looming ahead, the show's producers decided the musical side of the project might best be handled by experts. Thus Don Kirshner and his writing and production teams were brought in, making the first batches of Monkees recordings with session players, and the four Monkees only singing.
Nesmith, Tork and Dolenz were all experienced musicians before the Monkees; each had fronted or performed with bands, playing guitar and singing. None had played together before, though, and Dolenz was completely new to drums. (In preproduction for the show, Jones nearly disappeared behind a drum kit, and neither Nesmith nor Tork wanted to give up their guitars. Dolenz reluctantly volunteered, resolving to at least act like a drummer, until he could do the job.)
Originated as merely the fictional rock group from the television series (The Monkees (1966))of the same name, but emerged as a genuine band, partly from public demand they make good on their theme song and "come to your town" to play, and partly to silence music critics - and also other groups, who were jealous of what appeared to be undeserved "overnight" stardom.
Michael Nesmith wrote "Daily Nightly" (which appeared on the "Pisces" album) in reaction to the 1966 Sunset Strip curfew riot in Hollywood. Micky Dolenz sang, and played his new Moog synthesizer on the recording, becoming the first artist (and making the Monkees the first group) to include a synthesizer on a rock record. (A video of the song appears at the end of two second-season episodes of the show, in rare black-and-white.)
The only limitation on the Monkees' choice of music was that songs had to be owned or published by Screen Gems. Since this included both the Brill Building team and up-and-coming songwriters from around the country (like David Gates and Harry Nilsson), who made the Monkees top priority, it wasn't much of a limitation. The foursome had first crack at a wealth of great material, and never had to record a song they truly disliked. (The Screen Gems-only rule was finally lifted in 1969, when Davy Jones recorded Paul Williams's "Someday Man", written with Roger Nichols.)
One of the Monkees' concerns as their fame loomed was comparisons to The Beatles, and they knew the Beatles' first two movies were directly responsible for the look and sound of their show - and their first records. When the Monkees visited England in early 1967, they'd been playing their own concerts for a few months, and were preparing to record "Headquarters" by themselves, and were pleasantly surprised to find that the Beatles not only loved and praised their television show, but accepted them as pop-star peers. The Monkees each stayed at a Beatle's house (Mike with John, Micky with Paul, Peter with George, and Davy with Ringo), and attended some of the "Sergeant Pepper" sessions. Later that year, Beatles manager Brian Epstein sponsored them for three days of concerts at Wembley - the only live shows the Monkees gave in England, during the 1960s. (Touring America that summer, the Monkees played "Sergeant Pepper" almost constantly in their chartered jet.) Michael Nesmith thanks the Beatles on the Monkees' behalf, in the "Monkees on Tour" episode of the series.
Though he often called himself the "World's Greatest Tambourine Player", Davy Jones did learn the basics of rhythm guitar, bass guitar and drums during the Monkees' heyday, and sometimes took over for Micky or Peter onstage, freeing Micky to perform at stage front, or Peter to play keyboards or another instrument. (It also helped Davy write songs for the group.) Gretsch presented Jones with a custom-made 3/4-scale bass guitar.
Peter Tork noticed much about his Monkees audition was unusual or comical, so he joined the antics by walking into a wall when coming through a door. This got him noticed by the show's producers, but also led to his getting cast as the "dummy" of the group. Anyone who knew Peter (or listened to him for more than a minute) knew he was far from it, and the Monkees parodied the typecasting during their second season, and in the movie "Head". Tork was also the most musically versatile member, playing a dozen or more instruments.
Micky Dolenz wrote his first song "Randy Scouse Git" (which closes the "Headquarters" album) about the things he'd seen and heard on his first visit to England. The title was a phrase he'd heard on the BBC television show Till Death Us Do Part (1965), the "girl in yellow dress" was Juke Box Jury (1959) panellist Samantha Juste (whom he later married), and the "four kings of EMI" were the Beatles (who recorded for EMI), who'd given a party for the Monkees. When "Headquarters" was due to be released in England, a controversy happened over the song's title (which was actually rude slang for a sex-driven no-account from Liverpool), and the song was nearly replaced on the album. Since "randy Scouse get" didn't appear in the lyrics, RCA Victor (the Monkees' record label in England) offered to accept an alternate title for the song - which Dolenz promptly retitled "Alternate Title" for the UK. Media coverage had produced so much interest in the song that a single was also issued in England.
Michael Nesmith, already a published songwriter, was interested in writing for the Monkees, even before he tried out for a role, expecting that a hit show was bound to generate some healthy writers' royalties. He objected most strongly to the vocals-only policy imposed on the group, and Don Kirshner hoped that granting Nesmith two songs per album (which he was allowed to write and produce, but still not play on) would generate enough royalty money to appease him. Screen Gems also bought Nesmith's earlier songs from their publishers, so he could record them for the Monkees, and teamed him with more-experienced writers for new material. Nesmith wasn't satisfied, though, and when Kirshner refused to consider giving him even a B-side for an upcoming single (on top of not letting Nesmith play on his own records), Nesmith lost patience. (Kirshner chose who would write both sides of the singles, and preferred to use writers from his New York stable, saving the B-sides of potential hits as a kind of bonus for them.)
Producer Chip Douglas voiced his disappointment later that, with so much media coverage coming from the admission that the Monkees hadn't played on their first two albums, there wasn't similar coverage when "Headquarters" and "Pisces" were released, noting that they had played.