X-ray topography is one of several methods used by the semiconductor industry to measure stress of thin films deposited on single crystal substrates. A procedure to determine stress values directly from the X-ray topographic image by measuring the separation of the Kα1-Kα2 X-ray peaks is reviewed. Although less sensitive than the single-crystal technique, it has been found applicable to monitor stress levels in films such as CVD silicon nitride on silicon wafers. This technique may also be used to quantify the plastic deformation of wafers that is induced by semiconductor processes.