This study looks at the feasibility of producing fiber-reinforced diamond composites specifically for structural and tribological applications. Phase I research involves increasing the toughness of diamond matrix composites by adding continuous silicon carbide fiber reinforcement and by modifying the fiber/matrix interface. Mechanical properties such as, strength, strain-to-failure, and fiber pullout length are determined in bending and tensile testing at the Materials Department, University of California, Santa Barbara. The long term goal is a new class of composite materials which are tough and have high thermal conductivity and more corrosion and wear resistance than current ceramic composites.