Nurse practitioners (NPs) represent the fastest growing segment of the U.S. primary care workforce. Surveys of primary care NPs can help to better understand the care NPs deliver across different health care settings, the factors that impact NP job satisfaction and burnout, and the structural capabilities required to support their practice. The purpose of this article is to provide an overview of national sampling frames that can be used by researchers interested in surveying or studying the U.S. primary care NP workforce. We conducted an environmental scan and review of published literature on the NP workforce to identify data sources that can be used to sample primary care NPs. In this article, we (a) identify the data elements needed to develop an NP sampling frame and (b) describe national data sets that can be used to sample primary care NPs, including the strengths and weaknesses of each. This information is intended to facilitate research on the primary care NP workforce to inform practice and policy.