As part of our consultation for Colorado's Race to the Top Early Learning Challenge grant, Child Trends conducted a study to compare scores between the Early Childhood Environment Rating Scale-Revised (ECERS-R) and the latest version of the tool, the Early Childhood Environment Rating Scale-Third edition (ECERS-3). Colorado Shines, Colorado's Quality Rating and Improvement System (QRIS), currently uses cut-off scores on the ECERS-R to assign ratings at levels 3-5. If Colorado Shines were to transition to using the ECERS-3, it could have implications for the rating criteria, implementation of quality improvement supports, data systems, and communications. In this memo, we briefly describe the key differences between the design of the ECERS-R and ECERS-3 tools and the differences observed between these two tools in a sample of Colorado Shines programs. We also compare these findings to two other states' comparability studies and offer recommendations for next steps. An overview of the study methods is provided in the Appendix. (author abstract)