The sequential, layering techniques used to prepare multilayer materials result in significant structural incoherence due to deviations from the intended thicknesses within an elemental layer and local deviations from the average due to islanding of the depositing elements during deposition. We demonstrate that if the domain size of the structural incoherence is large compared with the wavelength of the scattering radiation, the structural incoherence manifests itself in the low‐angle diffraction pattern by attenuating the intensity of the subsidiary maxima relative to the Bragg maxima. We also show that the subsidiary maxima in the low‐angle diffraction pattern of a multilayer result from incomplete destructive interference from all of the interfaces, not just from the top and bottom surface of the film. A technique for incorporating structural incoherence when modeling the diffraction pattern of a multilayer structure is presented. The ability of this model to simulate the experimental diffraction pattern of an iron‐silicon multilayer is demonstrated.