A method of forming a component having an internal passage defined therein includes positioning a jacketed core with respect to a mold. The jacketed core includes a hollow structure formed from at least a first material and a second material, and an inner core disposed within the hollow structure. The method also includes introducing a component material in a molten state into a cavity of the mold, and cooling the component material in the cavity to form the component. The inner core defines the internal passage within the component.