Test methods were developed/adapted for complete mechanical characterization of textile composites in three dimensions [1-7]. Through-thickness tensile and compressive properties were obtained by testing short waisted blocks bonded to metal end blocks. The through-thickness shear behavior was determined using a short beam with V-notches under shear. Multiaxial states of stress were investigated by testing in-plane and through-thickness specimens under off-axis tension and compression at various orientations with the in-plane directions. Three types of failure criteria in three dimensions were investigated, limit criteria (maximum stress), fully interactive criteria (Tsai- Hill, Tsai-Wu)), and failure mode based and partially interactive criteria (Hashin-Rotem, Sun, NU). The latter, a new interlaminar failure theory developed by the authors [8,9], was found to be in excellent agreement with experimental results in the through-thickness direction, especially those involving interlaminar shear and compression.