This song is about a soldier in a war. In Rolling Stone magazine, Legend explained: "I don't have any personal experience, but I imagined what it would be like to be away from your wife, girlfriend, boyfriend, whatever, and not knowing if you'll make it home and could die at any point. And knowing that America is perpetually at war with somebody, either planning it or debating it."
Fall Out Boy's "The Kids Aren't Alright" song title is not a reference to The Offspring's 1998 single of the same name. It actually alludes to The Who's 1979 rockumentary film called The Kids Are Alright.