Recent results in electron/photon-stimulated desorption (ESD/PSD) from covalent systems are reviewed. This work has utilized Auger and photoelectron data, electron–electron and electron–ion coincidence data, and results from molecular orbital and configuration interaction calculations to provide an increased understanding of the desorption mechanisms in covalent systems. The systems reviewed include SiO2, Si3N4, H chemisorbed on Si, Ni, Pd, and W, and gas phase, condensed, and chemisorbed H2O and CO. Comparison of the ion desorption yields obtained from these systems reveals that atom–atom, adsorbate–adsorbate, adsorbate–substrate, and hydrogen bonding interactions can dramatically affect the ion yield. These covalent interactions are seen to increase the alternative decay rates of the excited states which initiate the desorption process.