This volume is based on material presented at the Second Materials Research Symposium of the National Bureau of Standards, held October 16-19, 1967. It provides a review of the application of spectroscopic and diffraction techniques to the study of the structure and dynamics of molecular solids. Invited papers on the theory and practice of the major experimental methods, including neutron and x-ray diffraction, neutron inelastic scattering, infrared and Raman spectroscopy and nuclear magnetic resonance, serve as a background for the more detailed presentation and discussion of results which follows. The topics covered in a series of invited and contributed papers include the lattice dynamics of molecular crystals, the spectroscopy and crystal structure of organic and inorganic solids and the dynamics of polymers.