The far-infrared spectra (33–500 cm−1) of crystalline cyanamide (NH2CN) and cyanamide-d2 have been recorded with polyethylene and silicon sample support plates. The laser Raman spectra have also been recorded from 40–1600 cm−1 for both molecules. No evidence was found for the inversion doubling and resultant low-frequency components of the NH2 and ND2 wagging frequencies previously proposed. While 14 of the predicted 15 infrared-active lattice modes were identified, only four of the predicted 24 Raman-active lattice modes were observed. Force constants were estimated from the observed infrared frequencies by use of modified Born–von Karman valence force field and Wilson-FG technique. Lastly, the distortion moment and effective charges were calculated using the method of Szigeti and Kurosawa. These results semiquantitatively reflect the difference in band intensities between the intra- and intermolecular vibrations.