Nowadays maquiladoras require improving processes and reducing costs in order to stay in the market and be competitive. Just in Time (JIT), the lean manufacturing tool, works specifically on materials handling, but critical success factors (CSFs) for its implementation are unknown. For this reason, in this chapter the results of a survey applied to 372 maquiladora workers of Ciudad Juárez (México) are reported. Six hypotheses are proposed and validated through a structural equations model executed in WarpPLS 5.0® software, where four latent variables related with Management Commitment, Human Resources, Suppliers and Quality benefits in a JIT environment are associated. Direct effects, indirect effects and total effects of each one of the variables are analyzed. The results show there is enough statistical evidence to state that there is a direct and positive impact of Human Resources on the obtained Quality in a JIT environment application.