A theoretical formalism to describe interface adhesion phenomena between materials has been developed. In this model electron densities, potentials, and adhesion energies of thin metal films at metal–semiconductor and metal–insulator interfaces are derived through a partially self–consistent calculation. The theory is based on a density–functional formalism applied to a simple model of the system in which the metal is replaced by a uniform positive background and the semiconductor by a continuum with a static dielectric constant. Numerical results of the metal electron density distribution and effective potential of Au–vacuum and Au–GaAs system, and the adhesion energy at Au–GaAs interface are presented. The interface energies are then used to estimate the adhesion strength and compare with experiment.