[en] Methods for interpreting thermoluminescence dosimeter (TLD) measurements made near nuclear facilities have been evaluated. These methods consist of techniques for estimating background radiation, i.e., all non-facility related environmental radiation, which can then be subtracted from TLD measurements of total environmental exposure to isolate any facility contribution. Tests were made with several years of background measurements at five sites in each of two geographical areas. Results are presented for monthly, quarterly, and annual intervals. At the sites studied, annual background exposures determined from monthly TLD measurements averaged about 65 mR. The best methods provided estimates of these annual exposures within 1.4 mR (1 standard deviation). Differences among the methods were small, but larger discrepancies are suggested for areas with radiation backgrounds of different composition and measurements of lower precision. This study indicated that with the optimum method and high precision data it is possible to determine an annual facility contribution of 10 mR within 1.5 mR