The NPI is an administrative tool of the Federal Centers for Medicare and Medicaid Services (CMS) used for processing claims and transferring health care information. The NPI can also be useful in studies of the health workforce. In this webinar, researchers at the University of Washington WWAMI Center for Health Workforce Studies and Rural Health Research Center share their experiences using NPI data for studies of the nation’s advanced practice nurse and physician workforces. They describe the strengths, weaknesses, and their remaining questions about using NPI data.