The ultimate goal of the project was to develop a new method, or adapt a current method, for determining bulk specific gravity (Gmb) of compacted hot mix asphalt (HMA) mixtures with wide applicability. The method must be repeatable and applicable to laboratory or field specimens for a wide variety of mixture types. A more reliable Gmb would result in more reliable HMA volumetric properties, specifically percent air voids. Consequently, dangerous pavement distress types such as rutting, bleeding, stripping, and age hardening (whose occurrence can often be predicted using percent air voids) could be avoided more often, ensuring a high degree of safety for the motoring public. The project goal was accomplished in three steps. In step 1, a literature review and survey of state departments of transportation revealed 13 existing Gmb determination techniques. In addition, the research team developed concepts for two new methods. The Tennessee Department of Transportation (TDOT) Monitoring Committee selected the 7 most promising methods for further study. In step 2, a feasibility study using 10 compacted HMA samples was conducted on the 7 selected methods to evaluate cost, logistical factors, and preliminary repeatability. The TDOT Monitoring Committee selected the 4 most promising methods for further study. In the final step, 50 compacted HMA samples and 4 aluminum cylinders were used to evaluate the precision and accuracy of the 4 selected methods. The dimensional analysis (AASHTO T-269) and the parafilm (ASTM D 1188) methods were found to form upper bounds for the sample air voids, while the SSD (AASHTO T-166) method was found to form a lower bound for true air voids. Although the true air voids can never be determined, the Instrotek Corelok System yields air void results in the range between the upper and lower bounds for the air voids. Finally, the Instrotek Corelok System was found to have the necessary precision, having an average coefficient of variation of 0.20% for the 50 compacted HMA samples used in the precision and accuracy step. Based on the results of the precision and accuracy study, the research team recommends the Instrotek Corelok System as the most widely applicable method for determining the Gmb of compacted HMA mixtures.