The contributions of vibrational spectroscopy, especially to the study of molecular structure and materials characterization was well established during the twentieth century. However, with the advent of time-resolved vibrational spectroscopy (TRVS) in the early 1970s, novel methodologies and tools enabled an experimental basis to extend measurements of static vibrational spectra (e.g., using mainly Raman and Infrared spectroscopies) to the examination of reactive and dynamic species (molecules, radicals, ions, excited electronic states) having lifetimes on the picosecond and longer time scales. TRVS continues to evolve in both the sophistication of the methods and the complexity of the molecular systems now being examined (e.g., enzymes, proteins, polymers, even living cells).