Two successful engine costing methodologies are outlined: RAND work sponsored by the USAF, and Navy work done at the Naval Air Development Center. RAND's time-of-arrival method addresses three phases--development, acquisition, and operating and support; and measures important characteristics--temperature, weight, pressure, specific fuel consumption, and thrust. The life-cycle cost estimates make the key cost drivers visible to a weapon system planner early in the concept formulation phase. The Navy method focuses on factors expected to affect the RDT&E and acquisitions costs of turbine engines. Historical data are used to establish CER coefficients for the RDT&E phase. Detailed studies relate the engines' material content to manufacturing costs. This method shows that lower costs can be achieved by (1) materials research to develop materials for the high temperature engine environment at lower costs, and (2) reducing the scrap rate during manufacturing.