I Do (The Castells song)

"I Do"
Single by The Castells
B-side"Teardrops"
ReleasedMarch 9, 1964 (1964-03-09)
RecordedNovember 1963 (1963-11)–January 1964 (1964-01)
RCA Victor Studio, United Western Recorders, and Gold Star Studios, Hollywood
Length1:47
LabelWarner Bros.
Songwriter(s)Brian Wilson, Roger Christian
Producer(s)Brian Wilson

"I Do" is a song written by Brian Wilson and Roger Christian, originally released as a single by American vocal group the Castells in March 1964. The recording was also produced and arranged by Wilson. The song's lyrics illustrate a young man getting ready for marriage. Its melody was derived from "County Fair", a song Wilson had earlier written for the Beach Boys.

According to Keith Mansfield, "the song didn't do much for the Castells, but it was a memorable experience [for Chuck Girard]". Musicologist Philip Lambert noted: "The 'I Do' intro is directly inspired by the instrumental accumulation in 'Be My Baby' and in the earlier [Phil] Spector production of the Crystals' 'Oh Yeah Maybe Baby' (1961), which have similar rhythms and instrumental combinations."