Erstwhile Records is an independent record label devoted to free improvisation, particularly the electroacoustic variety, contemporary, experimental composed music, and combinations of both. Erstwhile was founded by Jon Abbey in 1999, whose personality and tastes are closely identified with the label.

Characteristic label artists include guitarist Keith Rowe, percussionist Günter Müller, guitarist / turntablist Otomo Yoshihide, homemade electronics group Voice Crack, sine wave improviser Sachiko M, concrete artist Jason Lescalleet, guitarist / laptop composer Fennesz, guitarist Burkhard Stangl and synthesizer player Thomas Lehn, as well as younger musicians such as clarinetist Kai Fagaschinski. In recent years, also artists connected to the Wandelweiser group started releasing albums on the label, such as American composer Michael Pisaro.