Ethelene tetrafluoroethylene (ETFE) assembly is utilized on thousands of structures worldwide in both wall and roofs/skylight applications. It is used in multiple configurations, including the “pillow” configuration explored in this paper, and was installed at the Beijing National Aquatics Center (2008) (nicknamed the Watercube), the Eden Project in the United Kingdom (2001), Ferrari World in Abu Dhabi (2010), and U.S. Bank Stadium (home of the Vikings) in Minnesota (2016). Although the ETFE assembly can be used in lieu of traditional glazing and can be compared to traditional curtain wall or skylight assemblies in several ways, it also varies significantly from traditional glass glazing. Namely, it is a fraction of the weight, is transparent to ultraviolet and long-wave radiation (unless coated to perform otherwise), and responds to structural loads much differently than glass. This paper provides an overview of the ETFE pillow assembly, explores design and quality-assurance considerations for the assembly during construction, and draws on two case studies to demonstrate testing methodologies related to bulk water penetration: structural performance and deflection of the pillow assembly.