As part of its goal to minimize the requirements for critical and strategic minerals, the Bureau of Mines is conducting research to foster the use of domestically abundant materials such as molybdenum. This report describes the development of an investment shell molding technique that can be used to make castings of molybdenum and its alloys. The mold material is cubic zro2 with a monoclinic zro2 binder. The shell, formed by standard investment molding techniques described in the text, is prepared for molybdenum casting by firing for 6 hours at 1,550 deg c (2,822 deg f) or for 4 hours at 1,650 deg c (3,002 deg f). The resulting castings have predictable and reproducible dimensions with good detail. As-cast strength is poorer than the strength of wrought materials below 1,600 deg f. At and above this temperature, tensile strengths of cast and wrought materials are nearly equal. Aqueous corrosion of the castings in most media is insignificant.