Third song on Boingo's self-titled album. "Mary" tells the story of a girl who left a conservative home to see the world, live life beyond the small town experience, etc. and one day returns to her home town only to find that her family and friends can't accept who she is now. She has returned home physically but never can mentally. The meaning behind this song can be applied to more situations behind just this story of Mary: Anyone who has left one place or set of people to experience new things and returned to find him/herself no longer accepted by his/her old companions will surely be able to identify with this song.

The music for "Mary" is made up of both Boingo's rock band setup and an orchestra. The orchestra, conducted by Steve Bartek (the band's lead guitarist), dominates "Mary," primarily with a sweeping violin riff that repeats through most of the song. The orchestra's volume rises and falls throughout the song, ideally bringing the listener's heart with it.

The song's words and music were both written by Danny Elfman and produced by Elfman, Steve Bartek, and John Avila. The song is six minutes and twenty eight seconds long.