Grain growth is a fundamental behavior in materials processing that dictates the final microstructure and, thus, performance. Established grain growth models still fail to predict commonly observed, albeit irregular, behaviors like abnormal grain growth, in which a small fraction of grains grow faster than their neighbors. Our recent experimental observations using 3D x-ray diffraction microscopy methods reveal that curvature, the common assumed driving force for grain growth, is not a predictor of grain boundary velocity or direction of motion. Thus, the driving forces for grain growth must be re-examined to develop predictive models for both normal and abnormal grain growth. In this talk, I will compare experimental observations of growth in strontium titanate and alumina with Monte Carlo Potts simulations to interrogate the role of grain boundary energy anisotropy on microstructure evolution. These studies imply that sintering conditions can be used to control the final grain size and limit abnormal grain growth, which is demonstrated in a two-step sintering study of strontium titanate. Finally, I will demonstrate the limitations and opportunities of identifying the predictors for abnormal grain growth with 3D x-ray diffraction microscopy methods.