This chapter provides an overview of Lean Six Sigma methodology. It should give you a conceptual understanding of the philosophies and the rationale behind two of the most powerful process improvement methodologies in modern management—Lean and Six Sigma. It also puts forward the case for the high impact benefits that a combination of the two approaches can bring, which is far greater than using each of the methodologies alone. This chapter should serve as a brief but useful introduction to Lean Six Sigma for any stakeholder in an organization. It is essential to understand the basic concepts of the Lean Six Sigma methodology before we start the actual implementation. This chapter introduces these concepts, and the subsequent chapters of the book will deal with the actual implementation of Lean Six Sigma.