Growing Up consists of 16 tracks. The album's title track "Boo" is composed by Han Sang-won, who is best known for his melodies in songs "On days when I miss you" by Park Ji-hun of
V.O.S., and "Don't go, don't go, don't go" by Wanted. "Boo" is about a "charming friend of the opposite gender"; the lyrics tell the story of a haughty girl who does not care for the men around her. She falls in love with a boy to whom she had never given much thought. The follow-up song from the album, "You Know (Rock Ver.)", is the rock version of IU's song "You Know", which was more popular than the original version. The song portrays a young girl as she candidly expresses her feelings to the person with whom she is infatuated. ==Music videos==