This chapter presents an experimental and theoretical study of surface generation in ultra-precision grinding of hard and brittle materials. The study considers material properties, the relative vibration between the grinding wheel and the workpiece, machining parameters, and the phase shift of the grinding process. The Taguchi approach is employed to study the influence of machining parameters on the surface quality and shows the workpiece’s feed speed and rotational speed as vital factors. Experiments have been conducted to examine individual variables, and the results further show that the feed rate and the cross-feed distance have significant effects on surface generation. It is found that the spirals around the central area of the workpiece are the primary mechanism for surface generation, which originates from the synchronous relative tool-work vibration. The integral part of the ratio of the rotational speed of the grinding wheel’s rotational speed to the workpiece’s rotational speed determines the number of spirals, and its fractional part controls the spiral geometry. A theoretical model for predicting the single spiral generation has been developed to explain the accumulation of the phase shift and the geometry. The changeable feed speed near the end of grinding is also modeled, revealing the approximate straight lines around one circle in the central region. The simulated results indicate the theoretical models and the ground surface are in close agreement. Finally, a comparison of different surface generation mechanisms in grinding mold steel, tungsten carbide (WC), and reaction-bonded silicon carbide (RB-SiC) is investigated. It is interesting to note that the Spanzipfel effect contributes to the surface generation not only on ductile materials such as mold steel but also on brittle materials such as WC and RB-SiC. The Spanzipfel effect is most significant in grinding mold steel. For WC and RB-SiC, the ground surface contains both tensile and brittle regions in microfracture.