A successful Just in Time (JIT) implementation is based on human resources integration (managers, operators and suppliers) and other lean manufacturing techniques applied in the production process. However, the relationship between these variables is not easily quantified. This paper reports a structural equation model that integrates variables associated with JIT implementation: management commitment, human resources integration, suppliers and production tools and technique, which affect the benefits gained, and are integrated into nine hypotheses or relationships among then. The model is evaluated with information from 352 responses to a questionnaire applied to manufacturing industry, and partial least squares technique is used to evaluate it. The direct effects, sum of indirect effects, and total effects are quantified, and a sensitivity analysis based on conditional probabilities is reported to know scenarios associated with low and high levels in variables’ execution and how they impact the benefits obtained. Findings indicate that managerial commitment is the most important variable in the JIT implementation process, since managers are the ones that determine the relationships with suppliers, integrate human resources, and approve the lean manufacturing techniques and tools that support the JIT
