- Jimmy Martin — Lead Vocals, Guitar
- Bill Monroe — Tenor Vocals, Mandolin
- Rudy Lyle — Banjo
- Charlie Cline — Baritone Vocals, Fiddle
- Ernie Newton — Bass
Bill Monroe wrote “I Believed in You Darling,” and Bill Monroe and his Blue Grass Boys recorded it on 7 January 1954, possibly at the Bradley studio in Nashville. Jimmy Martin sang lead, with Monroe on tenor and fiddler Charlie Cline on baritone. Monroe played mandolin, Martin guitar, Rudy Lyle banjo and Ernie Newton bass. The same day produced “On and On,” “New John Henry Blues” and “White House Blues.” The song stayed on the shelf until 30 April 1956, when Decca issued it as the B-side of “On and On” (Decca 29886).
It is a song of broken vows. His sweetheart told him her heart would be true, and now she has left him: “Another has my sweetheart and the love that I once knew.” The nights are lonely, dreams of her haunt him, and he cannot say what went wrong: “What’s happened, little darling, I don’t know.”
Five weeks after the single came out, on 3 June 1956, the Stanley Brothers sang it at the Shenandoah Valley Bowl in Edinburg, Virginia. Carter Stanley sang lead and Ralph Stanley tenor, and the performance was issued years later on Together for the Last Time (Joy, 1971). The Bluegrass Album Band recorded the song as “I Believe in You Darling” on 22 September 1980 at 1750 Arch Studios in Berkeley, California, for The Bluegrass Album (Rounder 0140, 1981). Tony Rice sang lead, with Doyle Lawson on tenor, J.D. Crowe on baritone and fiddler Bobby Hicks singing bass, and Todd Phillips played bass. Peter Rowan sang it on The First Whippoorwill (Sugar Hill, 1985), with Alan O’Bryant and Sam Bush on harmony and Bill Keith on banjo. Ricky Skaggs recorded it as “I Believe in You Darlin’” for Ancient Tones in 1999, with Paul Brewster singing tenor.