The mechanical and failure behavior of a carbon-fabric/epoxy composite was characterized and appropriate failure criteria in three dimensions were proposed. The material investigated was reinforced with a fiveharness satin carbon fiber weave. In-plane tensile, compressive, and shear properties along the warp and fill directions were determined for the fabric composite and compared with a corresponding unidirectional composite having the same fiber and matrix constituents. 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. Three types of failure criteria in three dimensions were investigated, a limit criterion (maximum stress) , interactive criteria (Tsai-Hill, Tsai-Wu), and failure mode based or partially interactive criteria (Hashin-Rotem). Results obtained to date are in good agreement with a fully interactive criterion.