Unidirectional cord‐rubber specimens in the form of tensile coupons and sandwich beams were used. Using specimens with the cords oriented at 0°, 45°, and 90° to the loading direction and appropriate data reduction, we were able to obtain complete characterization for the in‐plane stress‐strain response of single‐ply, unidirectional cord‐rubber composites. All strains were measured by means of liquid mercury strain gages, for which the nonlinear strain response characteristic was obtained by calibration. Stress‐strain data were obtained for the cases of both cord tension and cord compression. Materials investigated were aramid‐rubber, polyester‐rubber, and steel‐rubber.