"When I Grow Up" was the first song that Tim Minchin wrote for Matilda, attempting to find a tone for the entire musical, drawing inspiration from his child.
Variety described the song as "the exuberant second act opener", yet noted "it’s impossible to miss the poignancy of inchoate feelings of loss and hope flooding beneath the surface".
[3] The Hollywood Reporter wrote "Only the most chronic misanthrope could fail to get misty-eyed when these mistreated kids glide back and forth on long rope swings singing “When I Grow Up.” That song’s soul-stirring mix of yearning and escape encapsulates what makes Matilda such a joy.
"[6] New York wrote "It must be a relief for the young actors — I know it is for the audience — when at the beginning of act two they get to sing a lovely, simple, Beatles-like tune called “When I Grow Up” while flying on rope swings high above the stage".
[9] Entertainment Weekly named it "the second-act show-stopper", and said the song "takes a simple, round-like melody and artfully sketches a pint-size perspective on the supposedly absolute freedoms of adulthood".