A curable composition comprising an epoxy resin and a hardener component is disclosed, and the hardener component comprises a polymer having a first constitutional unit of styrene, a second constitutional unit of maleic anhydride, and a third constitutional unit of salts of maleic acid, where the molar ratio of the epoxy group to the second constitutional unit is in a range of 0.5:1 to 5: 1. A prepreg that include a reinforcement component and the curable composition as well as an electrical laminate formed with the curable composition are also disclosed.