Blast, ballistic, and entry resistant operable window systems include a sliding exterior glazing panel assembly, a sliding interior glazing panel assembly, an exterior frame assembly that receives the sliding exterior glazing panel assembly, an interior frame assembly that receives the sliding interior glazing panel assembly, an exterior gasket for placement between the exterior frame assembly and the wall of the building, a central gasket for placement between the exterior frame assembly and the interior frame assembly, and an interior gasket for placement between the interior frame assembly and the wall of the building. Methods of installation in a wall of a building are also provided.