Abstract: A two-piece, or articulated, piston assembly for internal combustion engines, comprising a head composed of a top portion and a pair of pin bosses integral with it, a skirt portion, and a wrist pin mounted in the pin boss holes. The pin bosses are secured to a member restraining lateral deformation of the pin bosses. The restraining member may be the wrist pin itself, or defined by a cylindrical hollow pin fastened to the pin boss holes and housing the wrist pin. The thus formed structure prevents deformation of the pin bosses toward the cylinder liner, thereby imparting a higher strength to the piston assembly.