The article by Kameyama and coworkers (pp. 2851–2856) reports on a new strategy for reversibly photo-controlling the room-temperature magnetism in diluted magnetic semiconductors. Such fine and reversible control is obtained by coating ZnO nanoparticles with specially designed azobenzene-derivatized thiols. In addition to the photochromic groups the thiols act as a trigger for the generation of ferromagnetism at ZnOS interface. As a result, the nanoparticles show significant photoinduced changes in the saturated magnetization value at room temperature by alternating illumination with UV and visible light. These photo-magnetic effects can be attributed to photoinduced changes in the surface state at ZnO surfaces by photoisomerization of the azobenzene-derivatized ligands, which is accompanied by a change in the LUMO energy level.