Transparency is becoming increasingly important in the health care system. Many states and some private initiatives are endeavoring to expand transparency initiatives through synergy of price information and quality data. All-Payer Claims Databases (APCD) are key tools in these efforts, providing rich information about cost, utilization and outcomes at a population level, spanning the boundaries of time, care settings, episodes of care and payers. Currently, 11 states have an APCD and an additional 29 are exploring options, implementing an APCD, or have an existing voluntary APCD. This project, led by Stanford’s Center for Primary Care and Outcomes Research and funded by the Agency for Healthcare Research and Quality, seeks to lay the foundation for use of APCD data for measurement and transparency by exploring how can APCD data help improve affordability, efficiency, and cost transparency in the provision of health care. In particular, it focuses on how can APCD data be used for public reporting and other transparency efforts, what measures of price, utilization and quality are available or currently in use with APCD data, where major measurement gaps exist, and how key stakeholders can encourage use of APCD data for measure reporting.