This document summarizes the literature on the evolution from Six Sigma to Lean Six Sigma. It discusses that Six Sigma focuses on reducing variation while Lean focuses on eliminating waste. Lean Six Sigma combines these approaches. The document reviews key aspects of Six Sigma (DMAIC methodology), Lean (identifying seven types of waste), and Lean Six Sigma. It finds that Lean Six Sigma provides benefits like meeting customer needs, reducing costs and defects. However, barriers to implementation include difficulties in measurement and resistance from some workforces. Successful adoption requires leadership commitment, education and institutionalizing the approach.