In Washington state, the Working Connections subsidized child care program, along with the Seasonal Child Care and Child Welfare Child Care programs, supports children from low-income households, fostering their early learning and development while enabling families to maintain employment. Within these programs it is important to monitor patterns of child care subsidy use and related effects, as some populations may experience persistent interruptions in monthly payments, reflecting potential instability in children's lives (Henly et al., 2015). Evidence indicates that the consistency of children's subsidized care arrangements and deeper economic instability these patterns may reflect have important implications for children's development (Sandstrom & Huerta, 2013). However, it is not clear from the literature whether any negative effects associated with child care instability, or its underlying drivers extend to kindergarten readiness as a distinct outcome. The recent passage of the Fair Start for Kids Act (FSKA) in July 2021 has intensified interest in child care continuity as part of broader efforts to enhance access to child care and pre-K. In Washington state, researchers at the Department of Children Youth & Families (DCYF) have begun to evaluate the impacts of FSKA as part of a multi-year effort. The year one evaluation examined impacts of FSKA policy interventions on kindergarten readiness but the available data did not allow for a focused look at child care stability as a potential driver. This brief summarizes research, drawing on newly available data, which examines patterns of subsidy participation and stability and their connection to kindergarten readiness as measured by the Washington Kindergarten Inventory of Developing Skills (WaKIDS) assessment. This information provides a foundation for targeted interventions and policy improvements in the subsidized child care space and aims to inform ongoing evaluative efforts of existing investments through FSKA.