The book introduces the reader to the concepts of Scientific Molding and Scientific Processing for Injection Molding, geared towards developing a robust, repeatable, and reproducible (3Rs) molding process. The effects of polymer morphology, thermal transitions, drying, and rheology on the injection molding process are explained in detail. The development of a robust molding process is broken down into two sections and is described as the Cosmetic Process and the Dimensional Process. Scientific molding procedures to establish a 3R process are provided. The concept of Design of Experiments (DOEs) for and in injection molding is explained, providing an insight into the cosmetic and dimensional process windows. A plan to release qualified molds into production with troubleshooting tips is also provided. Topics that impact a robust process such as the use of regrind, mold cooling, and venting are also described. Readers will be able to utilize the knowledge gained from the book in their day-to-day operations immediately. The third edition includes a completely new subchapter "Melt Preparation", as well as much additional, revised, and updated material throughout the book. The revisions are deeply informed by the authors long and ongoing experience as a trainer, result in improved ways to conduct a study, perform experiments, or explain a concept.