Polypropylene (PP) is an important polymers that is used in a wide variety of applications. The global market for polypropylene has a turnover in excess of 65 billion US$. Many of the final properties of PP like molecular weight distribution and composition are determined by reactor operations. Understanding influence of operating parameters and hydrodynamics on the performance is therefore key to successful operation and design of fluidized bed PP reactors. This book outlines a multi-layered methodology for improving such the understanding. The book describes reactor engineering models to understand the normal and condensed mode of operation of PP reactors. It also explores the hydrodynamic behavior of PP fluidization using experimental analysis and Computational Fluid Dynamics (CFD) models. A framework for studying microscale droplet interactions with polymeric particles during condensed mode operations using high speed imaging is described. This book is addressed at practicing engineers who would like to get insight into polypropylene reactor operations. It is also directed towards researchers who have an interest in this area.