This book explains why the traditional materials planning environment, typically embodied by an Enterprise Resource Planning (ERP) system, is an ineffective support system for a company that wants to adopt Lean practices. It begins by defining supply chain management basics, including roles, objectives, and responsibilities from a traditional framework. Next, it describes Lean basics and explores the conflicts between Lean and the traditional framework. The book focuses on the materials management aspects of Lean, such as leveling work into the value stream, heijunka scheduling, standard work, and the concept of intervals, including Every Part Every Interval (EPEI). By combining traditional materials management tools such as Sales and Operations Planning (S&OP), with Lean manufacturing approaches and applying them to different manufactruing environments, the authors clarify the logic behind why you are doing what you're doing with Lean components and how they fit together as a system.