Expediting design and construction. Maximizing performance. Advancing technology and integration. The design and construction industry is increasingly focused on meeting higher performance standards while also reducing design and construction schedules. As a result, the use of unitized or prefabricated building enclosure systems also continues to grow. These systems may streamline construction, improve quality control, and enhance performance; however, they are not necessarily appropriate for every project. These systems require more significant coordination between the design and construction teams than typical enclosure construction methods; they often rely on challenging transitions at interfaces between different enclosure systems that cannot be accessed in the future; and, once manufactured, they cannot be easily altered to adapt to unforeseen site conditions. In this article, we discuss several popular unitized facade systems, reviewing the advantages and disadvantages of each. We explore design, constructability, coordination, durability, performance, continuity, and internal and external system integration. We review the benefits and challenges of unitizing the enclosure systems. Finally, we summarize various techniques and approaches to quality control during the design, fabrication, and installation phases of prefabricated building enclosure systems.