In this chapter, we critically review the globalization of the Reggio Emilia Approach (Reggio) in the past decades by focusing on the case of the United States. We first systematically review the original version of Reggio, including its origin, history, underpinning theories, the images of the child, the teacher, and the environment, as well as the role of the family, the community, and documentation. In addition, we reflect on Reggio’s understanding of the nature of knowledge construction and the multiple expressions of knowledge. We then historically review the influence and implementation of Reggio in the United States, including analyzing the similarities and differences in educational ideologies and pedagogical practices between Reggio and the United States and the conditions needed for professional learning. We conclude by summarizing lessons learned from this case study.