Stresses and strains were measured in triaxial specimens of dry sand under slow and dynamic rates of loading. Stress gages employing piezoelectric transducers were found to be sensitive to initial placement conditions, changes in the modulus-of-deformation of the surrounding soil, and lateral deformations of triaxial specimens approaching failure. Reliable stress measurements in triaxial tests below the critical lateral deformation values were made using calibration data of small triaxial specimens approximating the stress-strain relationship of actual tests. Strains were measured with mechanically uncoupled strain-sensing elements operating on the transformer principle. Strains were found to vary through the length of the standard specimens. In special frictionless end specimens, gage-measured stresses and strains were found to be the same as the average stresses and overall strains. At strain rates of 11 in/sec or higher, stress waves were produced with peak stresses a function of the rate of loading.