The cover picture shows a new method to illuminate quantum dots (QDs) by radiation luminescence as an internal light source. Taking advantage of the radioactive luminescent light at the visible and NIR range, many different fluorophores such as QDs can be exited to emit fluorescence for optical imaging. Three CdSe/ZnS core/shell QDs are chosen and irradiated by a β− emitter, 131I. The excited QDs can produce fluorescence for both in vitro and in vivo imaging. This study demonstrates an alternate strategy for the design of self-illuminating optical-imaging agents. Radiation-luminescence-excited fluorophores could also be readily adapted for dual-modality imaging. For more information, please read the Communication “Radiation-Luminescence-Excited Quantum Dots for in vivo Multiplexed Optical Imaging” by Z. Cheng et al., beginning on page 1087.