How might policymakers and educators utilize the work already being done as states redesign their accountability systems? The 2015 reauthorization of the Elementary and Secondary Education Act (ESEA), brought much needed attention to the performance of traditionally underserved subgroups of students. Supported by greater flexibility under ESEA waivers, state policy makers are designing more balanced systems of support and accountability that monitor and respond to performance assessments, opportunities to learn, the school environment, and access to equitable and adequate resources. In February 2015, a group of states launched a working group to share challenges and successes encountered during the redesign of their accountability systems. This cohort of 10 states--California, Colorado, Iowa, Kentucky, New Hampshire, Oregon, South Carolina, Vermont, Virginia, and West Virginia--represents diverse interests, and is committed to engaging in collective learning and action to transform their systems of accountability and support. Known as the 51st State Working Group, the cohort borrows its name from a framework developed by Linda Darling-Hammond, Gene Wilhoit, and Linda Pittenger, which proposed a "new paradigm" for redesigning key components of schooling. How might a hypothetical "51st state" design and implement policies and strategies to ensure all students are college, career, and life ready upon graduation? This report documents the progress made by the 10 states in the 51st State Working Group to transform their systems of accountability to support more meaningful learning opportunities for all students. The authors highlight state progress in the five key areas of the proposed framework: (1) Seamless pathways to college and career; (2) Flexibility and strategies for innovation; (3) Systems of assessment for and of learning; (4) Professional capacity-building; and (5) Accountability systems that draw on multiple sources. In addition to descriptions of each states activities in the key areas, the report looks ahead to new potential directions for accountability under ESSA.