The nemotogenic compoundp-methoxybenzylidene-p'-cyanoaniline in the nematic and isotropic liquid states has been studied by X-ray diffraction. A structure is proposed by comparing calculated intensities of a model with experimental diffraction intensities. The structure is comparable to the “herringbone” packing observed in many organic crystals. The procedure presented in this paper illustrates the practicability of using the method of comparison of experimental intensities with those calculated for a particular structural model. Comparisons of the experimental X-ray diffraction intensities and the radial distribution functions calculated from the intensities at different temperatures indicate an essentially unchanged structure throughout the nematic range but a gross structural change upon passing to the isotropic liquid state.