Preschool accountability systems, including Quality Rating and Improvement Systems (QRIS), seek to assess, monitor, and improve children’s outcomes across the early care and education (ECE) landscape. QRIS have a number of strengths, especially by focusing on classroom-level quality inputs for all children collectively across multiple domains that are well aligned with developmental science. This article considers how to build on the QRIS framework by highlighting children’s individual experiences within classrooms as a key indicator of quality in addition to the more traditional classroom-level measures. The article first provides the theoretical rationale and empirical evidence for focusing on children’s individual experiences based on new insights from developmental science. The article then illustrates key factors that relate to variation in children’s experiences, including child temperament, gender, age, and race/ethnicity. The article concludes by considering opportunities for innovation to better measure individual children’s experiences in QRIS. (author abstract)