Quality Rating and Improvement Systems (QRISs) provide an infrastructure that maintains as well as supports the enhancement of early childhood education (ECE) programs quality. It is being established worldwide. However, little is known about the implementation process and how this relates to implementation success. The purpose of this study was to have a better understanding of QRIS implementation through investigating QRIS in three regions within three countries (U.S., China, Singapore) based on implementation science framework (Fixsen, Naoom, Blase, Friedman, & Wallace, 2005), and cultural background of each country. A case study approach was used to examine the components of QRIS, implementation process, effect, and stage of each region’s QRIS. Results showed that the components of QRIS in each region looked different, with U.S. (North Carolina) having the most comprehensive components, and China (Beijing) and Singapore having fewer, although each still had critical components within their systems. The three countries also possess different values, strategies, and resources to support the implementation of QRIS. Based on each region’s implementation process, QRIS in North Carolina is in its full implementation stage with several major and minor adjustments going on; Beijing’s QRIS is at a mixed stage with variations in the development of different drivers; Singapore’s QRIS is clearly at an initial implementation stage. Implications for each region’s QRIS are discussed under their unique cultural, political, and historical backgrounds within each country. Further implications for implementation science framework as well as how it might be adjusted for each region’s QRIS implementation is discussed at the end