Optical phonon decay in hydrogen bonded molecular crystals is investigated by time resolved coherent Raman spectroscopy. The importance of low frequency motion in chemically important systems is examined. The low temperature phonon lifetimes, in general, were found to decrease monotonically with phonon frequency. This reflects the density of accepting phonon modes and the decay mechanism. Phonon relaxation in the complicated hydrogen bonded crystals of nucleic acid bases indicate that a more detailed theory is needed than that used to describe phonon decay in hydrogen bonded crystals of amino acids. The measurement of the lifetime and frequencies of the low energy modes can be important to an understanding of chemistry in condensed phases. Picosecond CARS has been used to establish the timescales involved for these motions and has enabled us to uncover the relative lifetimes of many optical phonons in the same crystal.