A mong the high priority outcomes sought in reforming American health care are greater provider accountability, better processes of care and improved clinical outcomes, more satisfying care experiences for both patients and caregivers, and greater operational efficiency. Performance measurement is an essential tool for implementing strategies aimed at achieving these goals.In this issue of the Journal, Powell and colleagues describe a number of unintended consequences of implementing performance measurement in the Department of Veterans Affairs (VA) Health Care System, 1 an early adopter of system-wide performance management. [2][3][4][5] While there are significant limitations in generalizing the findings of this retrospective qualitative study, it is an important contribution to the growing body of evidence documenting the complexities of health care performance measurement and a poignant reminder that performance measurement is a tool that cuts both ways.Powell et al, report the findings of 59 semi-structured individual in-person interviews of primary care staff members and facility leaders at four VA facilities of varying size and levels of performance. 1 They found local implementation of VA's national performance measurement system led in some instances to provision of inappropriate clinical care, decreased provider attention to patient concerns and service, and compromised patient education and autonomy, as well as some adverse effects on primary care team dynamics. They additionally observed notable variation among the facilities in how performance data were shared with front line clinicians, strategies to improve performance, and application of rules. Concerns about the burden of reporting, clinical importance of some measures, inflexibility of automated clinical reminders and inequity in allocating financial rewards for improved performance were also commonly voiced in the interviews. While their study was not designed to determine the circumstances that led to the unintended consequences, they noted that in many cases the problems appeared to stem from local implementation methods rather than from the nationally determined performance measure definitions and policies. They observed both unintended positive and negative consequences, but described only negative effects in this report.Performance measurement is a tool widely used in diverse industries to monitor progress towards achieving identified goals and is increasingly being used in health care, although still limited due to health care's poorly developed infrastructure supporting measurement processes and application of measure results, as well as the nascent state of health care performance measurement science. Current health care reform efforts portend far greater use of performance measurement.Multiple perils and pitfalls of performance measurement have been identified in recent years, especially in development and selection of measures, data collection, reporting and use of results. [6][7][8][9][10][11][12][13][14][15][16] Similar to any gene...