The potential for significant performance increases, using ceramic materials in un-lubricated rolling element bearing applications, has been the subject of research over the past two decades. Practical advantages over steel include increased ability to withstand high loads, severe environments and high speeds. However, widespread acceptance has been limited by the inability to predict wear life for ceramic bearing applications. In this thesis, the rolling contact wear of 52100 bearing steel and Over-aged Magnesia-Partially-Stabilised Zirconia (OA-Mg-PSZ) ceramic are examined using a newly developed rolling contact wear test rig. The new wear test rig simulates the system geometry of an un-lubricated hybrid (ceramic and steel) ball bearing. The new wear test rig is versatile in that it allows low cost samples to be utilised resulting in a larger number of samples that can be tested. Wear samples of 52100 bearing steel and OA-Mg-PSZ produced by the new wear test rig were examined for mass loss and wear depth. The wear behavior of both the steel and ceramic material showed a dependence on operating variables time and load. Load was varied between 300N to 790N. Typical mass loss after 1 hour of testing 52100 bearing steel at 790N was 0.03 grams as compared to OA-Mg-PSZ which was 0.001 grams. The rolling contact wear of the OA-Mg-PSZ was an order of magnitude lower than that of the 52100 bearing steel. The wear mechanism for 52100 bearing steel was typical of plastic deformation and shearing near and below the surface of rolling contact. Once cracks extend to reach the surface, thin flat like sheets are produced. In OA-Mg-PSZ the wear mechanism initially is that of plastic deformation on the scale of the surface asperities with asperity polishing occurring followed by lateral cracks and fatigue spallation. Results obtained using the new rolling contact wear test rig led to the establishment of a new equation for wear modeling of 52100 bearing steel and OA-Mg-PSZ ceramic materials.