BYO Split Series Vol. 4 is a split album released in 2002 as the fourth entry in BYO Records BYO Split Series. The album features twelve tracks by US punk bands The Bouncing Souls and Anti-Flag. Each band covers one song originally by the other, with The Bouncing Souls performing "That's Youth" and Anti-Flag performing "The Freaks, Nerds & Romantics". Other covers are Cock Sparrer's "We're Coming Back" and Sticks and Stones' "Less Than Free" by The Bouncing Souls and the Buzzcocks' "Ever Fallen In Love" by Anti-Flag. The remaining tracks were originally recorded for this album.
For the release of this album, The Bouncing Souls and Anti-Flag toured nationally together.