Using low-angle laser light-scattering (LALLS) and multiangle laser lightscattering (MALLS) techniques, absolute molar mass averages were determined for a wide variety of polymers in the Methocel(TM) product line produced by The Dow Chemical Company. These data were correlated to GPC molar mass averages obtained from column calibration using pullulan standards. It was determined that the pullulan equivalent molar mass averages overestimated the values determined by light scattering by a factor as high as 3.2. Mark-Houwink parameters were calculated based upon values for the pullulan standards and application of the universal calibration concept. Sample preparation issues and chromatographic conditions that impact data quality are also presented.