This book reports four structural equation models (SEM) for quantifying the relationship between the most important lean manufacturing (LM) practices applied to the manufacturing industry. The SEMs are evaluated using 220 responses to a survey applied to manufacturing companies applying LM principles in the production system and are related to: distribution and maintenance, production process and quality system, supply chain and quality, and an integrator model. The findings identify the most important activities for every LM practices and how they are related. These relationship' values will help administrators, managers, engineers to focus their efforts on these most important activities, facilitating the decision-making process.