In our descriptive study, we analyze the QRIS ratings of ECE programs in one large California county to answer policy and practice important research questions within the ECE field. Specifically, our study aims to answer: (1) To what extent do participating ECE programs’ tier ratings change over time?; (2) To what extent do structural and process quality element scores as measured by the county-level QRIS change over time?; and (3) To what extent do indicators of classroom quality, as measured by the CLASS, change over time? Through addressing these research questions, we seek to further understanding of how participation in large-scale quality initiatives, like QRISs, is associated with change in ECE providers’ structural and process quality, and whether and how the relationship may differ across provider type. (author abstract)