Two general types of energy-dependent cross-section variations are demonstrated for inverse photoemission: (i) an atomic effect based on the spatial extent of the wave function and (ii) a solidstate effect caused by peaks in the Fourier spectrum of bandlike states. As examples, data are shown on the photon-energy dependence of (i) the 5d- to 4f-intensity ratio in Gd and (ii) the intensity of broken-bond states on Si(111).