We present a first attempt to predict heterojunction band lineups from the bulk band structures of the participating semiconductors, without invoking free surface properties. Band structures and electrostatic potentials are calculated by a self-consistent pseudopotential. A simple electrostatic matching scheme lines up the electrostatic potentials, and through them the band structures. Predicted lineups are in good qualitative agreement with known lineups, and even in some cases [particularly GaAs– (Al,Ga)As] in good quantitative agreement.