The song is known for its minimalistic lyrics, that consist only of: "They only want you when you're seventeen / When you're twenty-one / You're no fun / They take a polaroid and let you go / Say they'll let you know / So come on".
The music video of "Seventeen" featured the band playing the song in a special black room, that includes some neon lights. The black room is separated by a wide window from another larger grey room. In the grey room is a weighing scale, a telephone and a stand with an old television and another device that looks like a VCR. Mira Aroyo and Helen Marnie are in front of the black room near that window, and Daniel Hunt and Reuben Wu are in the back. Each member wears a black uniform and plays a synthesizer.
The video starts with a group of schoolgirls and a female professor entering the grey room from a long lobby. The girls start dancing while the band performs the song and also looks at them through that wide window. From time to time the professor removes one of the girls. At the end of the song, there's only one girl left in the grey room. Then she starts staring at the band through the window.