An axial-torsional testing system, consisting of an MTS loading frame ( 9.8 kN/113 N-m) and Testware-SX control, was developed for evaluating the multiaxial behavior of cohesive soil. The capabilities of the testing system include automated control of three axes (axial load/ displacement, torque/rotation, and confining pressure) under static and dynamic conditions. Description of a custom-designed triaxial-torsional shear cell developed for this study is presented. Uniform and reproducible specimens (hollow and full cylinder) were obtained with a slurry consolidation technique. As an example for implementing software control, procedures are described for performing K sub o consolidation with an electropneumatic transducer in conjunction with an automated volume change device. An optical technique developed by the authors for measuring local strains under axial-torsional loading is also described. Initial test results associated with an undrained constant rate of strain axial and pure torsional shear testing on isotropically consolidated hollow-cylinder kaolin clay are presented. Aspects associated with repeatability are discussed. The test results are being used to evaluate the influence of the inclination of major principal stress on the shear strength and pore pressure behavior of isotropically consolidated clay. A qualitative discussion related to global versus local deformation patterns of hollow-cylinder specimens under axial and torsional loading is also presented.