Building Enclosure Commissioning (BECx) is a quality-oriented process intended to verify that a building enclosure’s design and construction meet the Owner’s Project Requirements (OPR). The BECx process also helps to enhance the performance of building enclosure components and assemblies through technical assistance provided by the BECx Provider (BECxP) to the project team. However, without proper execution or integration into the project, BECx can be an underutilized tool. For instance, the BECxP may be introduced to the project after the design and project budget have been established, thereby narrowing the opportunities to provide technical recommendations to the project team on design alternatives that more efficiently meet the OPR. Additionally, the full project team must be committed to and active in the process to realize its full benefit. In some cases, the BECx process is viewed as a box to check and the BECxP is not wholly integrated into the project team. Finally, recommendations made by the BECxP may be construed as undermining decisions made by other project stakeholders. This paper will discuss the challenges to full integration of BECx into a project and, through a recently completed case study example, will illustrate successes, failures, and lessons learned regarding the BECx process. Key milestones in the BECx process will be discussed to illustrate where the project fell short of expectations and where potential issues were successfully addressed through recommendations by the BECxP and responsive actions by the project team. We will identify how the BECx process affected design and construction details such as window-to-wall interfaces, air and water control layer detailing, and roofing, some of which were successful and some of which fell short of expectations. The BECx team will share lessons learned from this case study that are now being utilized to improve the process for its projects moving forward.