We present a review of recent efforts aimed at understanding interfacial charge transfer at the single molecule and single nanoparticle level using the combined methods of traditional electrochemistry and optical spectroscopy with high spatial, spectral, and temporal resolution. Elastic light scattering, surface enhanced Raman scattering (SERS), fluorescence, and electrogenerated chemiluminescence (ECL) techniques have been demonstrated to be powerful tools for the study of interfacial charge transfer events involving a single molecule or nanoparticle and for the characterization of nanostructured electrodes. It is shown that these optical methods enable the exploration of electrochemical events with improved temporal and spatial resolution which are usually obstructed by the ensemble averaging inherent in conventional electrochemical methods. In this report, the current status of the field is reviewed and challenges for future work are discussed.