Earlier results from computer simulation studies suggest a correlation between the spatial distribution of stacking errors in the beta -SiC structure and features observed in XRD patterns of the material. Reported here are experimental results obtained from two types of nominally beta -SiC specimens, which yield distinct XRD data. These samples were analyzed using high-resolution transmission electron microscopy (HRTEM) and the stacking error distribution was directly determined. The HRTEM results compare well to those deduced by matching the XRD data with simulated spectra, confirming the hypothesis that the XRD data are indicative not only of the presence and density of stacking errors, but also that it can yield information regarding their distribution. Moreover, the stacking error population in both specimens is related to their synthesis conditions, and is similar to the relation developed by others to explain the formation of the corresponding polytypes.