Semiconductor photochemistry and photophysics play an important role in the broad field of supramolecular photochemistry. The unique properties of nanocrystalline semiconductor particles—which include quantum size effects on the bandgap, high surface area which is optimal for interfacial reactions, good photo- and thermal stability, and compatibility with the environment (i.e., “green” chemistry)—have led to an explosion of interest in the field. This volume of the Molecular and Supramolecular Photochemistry series provides chapters, authored by experts in the field, that discuss the area of semiconductor photochemistry and photophysics and highlight recent important advances in the area.