This article investigates experimentally the influences of contact pressure and surface preparation on the thermal contact conductance across stainless steel (AISI 304) and aluminum (6061). The thermal contact conductance was measured for eight pairs of nominally flat metal specimens in a vacuum environment. Five pairs consisted of one stainless steel (304) specimen and one aluminum (6061-T6) specimen, one pair consisted of two aluminum (6061-TO) specimens, and the remaining two pairs consisted of two aluminum (6061-T6) specimens. The aluminum specimens in the last three pairs were re-heat-treated after surface preparation to eliminate work-hardening effects. The contacting surfaces were in combinations of bead-blasted with bead-blasted or bead-blasted with ground. All experiments were conducted at room temperature, and the contact conductance was measured as a function of contact pressure from 1.38 to 9.12 MPa. Predictions from existing elastic and plastic contact models were correlated,vith the data obtained. Experimental findings indicate that the contact conductance was a strong function of contact pressure, but not of surface roughness. Since both contact models predict a direct relationship between conductance and surface roughness, neither model correlated well with the data throughout the range of surface conditions tested. In addition, the extra oxide acquired during quenching caused larger interfacial resistances, and a reverse hysteresis in the first loading/unloading cycle for the re-heat-treated aluminum (6061-T6) pairs.