We have presented a systematic experimental and theoretical investigation electric-field-gradient (EFG) tensor and chemical shielding (CS) tensor in crystalline amides. Three O-17-labled secondary amides, R1C[O-17]-NHR2, have been synthesized: benzanilide (1). N-methylbenzamide (2), and acetanilide (3). Analysis of O-17 magic-angle spinning (MAS) and stationary-NMR spectra yields not only the magnitude but also the orientation of the carbonyl! O-17 EFG and CS tensors, For compounds 1-3, the carbonyl O-17 quadrupolar coupling. constant (QCC) and the span of the chemical shift tensor are found to be in the range of 8.5-8.97 MHz and 560-630 ppm, respectively. The largest O-17 EFG component lies in the amide plane and is perpendicular to the C = O bond, whereas the smallest component is perpendicular to the N-C = O plane. For the carbonyl O-17 CS tensor, the principal component with the largest shielding, delta (33) is perpendicular to the amide plane, and the tensor component corresponding to the least shielding, delta (11), is in the amide plane approximately 20 degrees. off the direction of the C = O bond. Extensive quantum chemical calculations using density functional theory (DFT) have been performed for both isolated and hydrogen-bonded molecules of compounds 1-3. The calculated carbonyl O-17 EFG and CS tensors from the latter molecular models,are in reasonably good agreement with the experimental values. In particular, the B3LYP/D95** EFG calculations overestimate the carbonyl O-17 CC by approximately 0.5 MHz The B3LYP/D95**/GIAO shielding calculations yield a linear correlation between the calculated and experimental data (slope = 1.125 and R-2 = 0.9952). The quantum chemical calculations indicated that the intermolecular C = O . . .H-N hydrogen-bonding interactions,play an important role in determining the carbonyl oxygen EFG and CS tensors for an amide functional group.