Further reading: Yes I Will at Wikipedia.
Yes I Will with a different title, on their first album The Monkees (1966).
Of the two writers, Gerry Goffin (1939–2014) is the better known, as songwriting partner with his wife Carole King.
Russ Titelman (b. 1944), a singer-guitarist-composer who was an early associate of Phil Spector, became known as a producer for the likes of Eric Clapton, Little Feat, George Harrison, and Brian Wilson. He also wrote a number of choice but often overlooked songs in the 60s, notably the sublime What Am I Gonna Do With You (Hey Baby), written with Gerry Goffin and recorded by The Inspirations, The Chiffons, Lesley Gore and Skeeter Davis.
See also Little Pattie – Little Things Like That, another Titelman co-composition.
Further reading: 1. Some Russ Titelman compositions are listed in a Spectropop post by Declan Meehan, for whom Titelman is one of the greatest unsung co-writers or writers… especially in the girl group genre. 2. Again at Spectropop, Mike Edwards also lists some of Titelman’s songs and co-writers. 3. Annotated playlist from a Spanish radio show dedicated to Titelman productions and compositions (at Flor de Pasion). 4. Timothy White interviews Russ Titelman (Billboard, 1996, reprinted at Spectropop.com