This international standard specifies a procedure for determining the apparent interlaminar shear strength (ILSS) of fibre-reinforced plastic composites by the beam method. The method is suitable for use with the following materials: - fibre-reinforced thermoset and thermoplastic composites incorporating unidirectional or non-unidirectional reinforcements such as mat, rovings, woven fabrics, woven rovings, chopped strands, combination and hybrid reinforcement, sheets made from preimpregnated material (prepreg).