Disco 4 also known as Disco Four is the eighteenth album by the UK electronic music duo Pet Shop Boys and the fourth in the band's "Disco" series. It was released on 8 October 2007, on compact disc and vinyl. It was not released on digital download, due to licensing difficulties for each track. The album is mainly a compilation of Pet Shop Boys remixes of songs by other artists, a first among any of their releases to date. It also includes a previously unreleased mix of "Integral" and the maxi-mix of "I'm with Stupid", previously released on the Japanese edition of Fundamental.