Purpose: The theory of constraints (TOC) methodology and its drum-buffer-rope (DBR) production planning and control system are well suited to managing production plants in complex environments. The objective of this study was to design an evolution of the systematic process for implementing the third step of the TOC methodology in make-to-order environments. Design/methodology/approach: Since the research concerned a real context and the phenomenon under investigation is contemporary, a case study was chosen as the research methodology. Findings: The study investigated, through a case study, the phases and steps necessary for the systematic process to be successfully implemented in a make-to-order environment. Originality/value: The three main contributions to the systematic implementation process for the third step of the TOC model are identified as the design of the last version of the systematic process, the integration of sales and operations through the TOC methodology and the introduction of the demand-driven adaptive enterprise model’s capacity buffer