Core–valence–valence (CVV) Auger spectroscopy can now be used as a local valence probe of molecular, chemisorbed and solid-state species. Analysis of Auger data has led to the discovery of localized multihole valence excitations in covalent systems, and there is evidence that these excitations may play a major role in the dissociation of large molecules and in stimulated desorption from semiconductor surfaces. The basic physics behind the CVV decay is summarized. The relative importance of factors that influence the decay amplitudes (local charge density, initial-state screening, valence nonorthogonality, and configuration mixing) and the Auger energies (independent vs coupled final-state holes) is explored.