
Music historian Charles Granata wrote that the song "best exemplifies the musical growth" through its "effective combination of odd sounds" and its "full and round" vocal harmonies. "When I Grow Up" features multiple key changes, a hook based on a dissonant, functionally ambiguous chord, tempo stretches, and a long pause as a climax.

It is one of the first rock songs to discuss impending adulthood and is possibly the earliest US top 40 song to contain the expression "turn on" (from the lyric "Will I dig the same things that turned me on as a kid?"). Ĭritic Richard Meltzer later cited "When I Grow Up" as the moment when the Beach Boys "abruptly ceased to be boys". Academic Jody O'Regan interpreted the line as Wilson admitting that he had doubts about his marriage. To this effect, the narrator poses such question as "Will I love my wife for the rest of my life?" That line in particular marked the first instance of a Beach Boys song discussing falling out of love with someone, as opposed to just being in or out of a relationship. The lyrics describe a boy who is anxious of when he stops being a teenager. Wilson later revisited the topic of manhood in the 1966 song " Child Is Father of the Man". In his 2016 memoir, Love wrote that the song was "probably influenced" by Murry Wilson, who constantly challenged Brian's manhood. I don't think I will now, and that is what inspired 'When I Grow Up'." In a 2011 interview, he commented that when he wrote the song, he had a dismal view of his future.

At the time, Brian told the Birmingham Post, "When I was younger, I used to worry about turning into an old square over the years. "When I Grow Up (To Be a Man)" was written and composed by Brian Wilson with additional lyrics by Mike Love.
