Transition metal oxides exhibiting a bistable resistance state are attractive for nonvolatile memory applications. The relevance of oxygen vacancies for the resistance-change memory is investigated by X-ray fluorescence (see figure), infrared microscopy, and X-ray absorption spectroscopy using Cr-doped SrTiO3 as an example. The microscopic origin of resistance switching in this class of materials may be due to an oxygen-vacancy drift occurring in close proximity to one of the electrodes.