Child Trends is conducting a validation study of Arizona’s Quality Improvement and Rating System (QIRS), known as Quality First. In Phase I of the study (2015–2017), Child Trends examined whether Quality First’s rating system worked as expected and whether it effectively distinguished between different levels of quality. In Phase II (2018–2020), Child Trends is evaluating the fidelity of implementation of Quality First components, such as coaching, assessment, specialized assistance, professional development, and financial incentives. We are also examining whether these Quality First components effectively contribute to programs’ quality improvement. In addition to the validation study of the current Quality First model, Child Trends is evaluating a field test of a redesigned model that intends to use resources more efficiently so that Quality First can serve more programs.