In any geologic settings, the complete characterization of the natural gas hydrate system requires an overlapping approach that includes direct sampling, downhole logging, and geophysical remote sensing. Due to the difficulty and cost of obtaining seafloor samples, scientists ultimately aspire to extract maximum information from downhole logs and geophysical data. Unfortunately, the inherent complexity and heterogeneity of natural systems often renders the interpretation of such indirect data difficult. As a means of calibrating logs and geophysical techniques, there is an important role for laboratory studies on controlled systems with known grain characteristics, formation history, and gas hydrate concentration. Such laboratory efforts lead not only to new effective media and mixture models that can be extended to interpret natural sediments, but also to a better mechanistic description of the interaction between hydrate and sediments. We have conducted an extensive series of laboratory experiments to measure the thermal, electrical, and mechanical properties of fully saturated, homogeneous sediments containing synthesized THF hydrate, with support from the ChevronTexaco Joint Industry Project (JIP) on Methane Hydrates. Test conditions span most of the range represented in natural marine sediments (grain sizes of 1 to 120 μm), gas hydrate concentrations of 0% to 100% in pore space, and effective confining pressures of up to 2 MPa.