Surface-enhanced Raman spectroscopy (SERS) has single molecule (SM) sensitivity for adsorbates that possess an electronic chromophore resonant with the excitation laser. Examples of recent SMSERS studies that will be discussed include: proof of single molecule sensitivity; nanoscale temperature measurement, direct detection of products in plasmon-driven chemistry; and the observation of single, heterogeneous, one-electron transfer reactions. Tip-enhanced Raman spectroscopy (TERS) combines the single molecule sensitivity of SERS with sub-nanometer spatial resolution making it an ideal tool for studying nanoscale chemistry in ultrahigh vacuum (UHV) and electrochemical (EC) environments. UHV-TERS studies of porphyrin and perylenediimide adsorbates on Ag(111), Ag(100), Au (111), and Cu(111) will be presented along with the first electrochemical TERS (EC-TERS) study of a nanoscale redox reaction.