For decades, policymakers in the U.S. have leveraged accountability policy as a governing tool to lift school performance and close the achievement gap. Accountability become so widespread that it arguably became a "policy paradigm" with the passage of the federal No Child Left Behind (NCLB) Act in 2002. Yet after just 13 years of implementation, policymakers replaced NCLB with the Every Student Succeeds Act (ESSA), which gave states more control over the policy tools and mechanisms to regulate school improvement. This qualitative project captured the evolution of the accountability paradigm by studying the policy ideas and moral narratives of policy elites in California and Tennessee during the transition period between NCLB and ESSA. The study finds that interview participants legitimized the core design features of ESSA, but attached their underlying worldviews and beliefs to the flexible design features, which created unique accountability models with different institutional arrangements.