An integrated data system (IDS) that links information from separate administrative data systems offers policymakers, program administrators and researchers a powerful tool to analyze interactive effects across systems and make more informed decisions to improve outcomes for vulnerable families. This case study discusses how two states (Washington and Wisconsin) have used their integrated data systems to design and conduct evaluations to understand how child support enforcement policies and Temporary Aid for Needy Families (TANF) benefits affect the length of time children spend in child welfare placements. With this information, state policymakers are taking action to improve child welfare outcomes by enabling their child-focused systems to work together more effectively.