The implementation of a Manufacturing Execution System (MES) is a key process for companies seeking to optimize their operations on the road to Industry 4.0. is a key process for companies seeking to optimize their operations on the road to Industry 4.0. This type of system allows for real-time monitoring and improved decision making among other benefits. However, to ensure a successful implementation of an MES, it is crucial to establish a solid and aligned relationship with the technology provider, who must thoroughly understand the needs and objectives of the organization. In this article, Josep María Riera details the fundamental aspects that should be requested from a supplier to ensure an effective and efficient MES implementation, from initial planning to ongoing support and maintenance.