•We examined quality change and supports in a quality rating and improvement system.•For both centers and homes, quality increased over time and was associated with duration.•For centers, scholarships were associated with quality change.•Supports were more associated with quality change for programs with shorter duration. This descriptive study investigated the associations between change in quality and quality improvement supports among center-based programs and family child care homes within Miami-Dade County, Florida's tiered quality rating and improvement system (TQRIS), Quality Counts. The TQRIS supports included grants and financial awards for materials and equipment, educational scholarships for staff, and on-site technical assistance to raise quality. Data were extracted from a TQRIS information management system on 412 programs (342 center-based programs and 70 family child care homes) participating in the TQRIS from 2008 to 2013. Results indicated that across both types of care (centers and homes), quality increased over time. Duration, or amount of time in the TQRIS, was significantly related to quality change. Scholarship amounts received were also significantly related to quality change for centers. Interactions between dosage and supports suggested that some supports were associated with quality change for programs that were in the TQRIS for a shorter duration. The consistent findings regarding duration in the TQRIS and scholarships suggest the importance of supporting programs and their staff. Policy implications related to building TQRISs are discussed.