Initial feasibility findings of a research program directed toward the development of a practical tool for rapid in situ determination of material properties (modulus and damping) of soft to medium-stiff clays over a wide range of strain (0.0001% to 10%) are presented. The motivation for this work is discussed in terms of both the sensitivity of earthquake ground response analyses to input material properties, as well as the limitations of existing design methodologies for specifying material behavior. The scope and objectives of the research program are outlined. Results are presented from numerical analyses used to establish typical stress and strain fields caused by borehole installation. The merits of several tool-design alternatives are considered, and preliminary design concepts for a new tool called the “Freestanding Torsional Shear (FTS)” device are introduced. Critical issues and future directions of the research program are discussed.