Research Findings: A statewide study of preschool classroom quality was conducted using 3 distinct classroom observation measures in order to inform a statewide quality rating system. Findings suggested that Tennessee preschool classrooms were approaching "good" quality on the Early Childhood Environment Rating Scale-Revised (ECERS-R) and provided a mid-to-high emotional and engaging climate as indicated by the Classroom Assessment Scoring System (CLASS) domains of Emotional Support and Student Engagement. However, classrooms were only minimal on the Early Childhood Environment Rating Scale-Extension and the CLASS Instructional Support domain. Past performance on a state quality rating assessment consistently predicted the current quality of preschool classrooms as assessed by all 3 measures. Lead teachers' education in early childhood and experience were also predictors across quality measures. Practice or Policy: Tennessee preschool classrooms scored higher on the ECERS-R, which is the measure utilized in the statewide Quality Rating and Improvement System. However, classrooms generally performed poorly on measures of instructional support and curriculum. This finding illuminates the importance of the tool selected to measure quality in state quality rating and improvement systems and has implications for policy as states work to build systems that enhance quality in early care and education. (Contains 6 tables.)