Over the last several decades, nurse practitioners have assumed increasingly important roles in the healthcare system. However, some state scope of practice laws limit the ability of nurse practitioners to deliver care by requiring physician supervision of their practices and prescribing activities. A robust literature has evolved around examining the role of these scope of practice laws in various contexts, including labor market outcomes, healthcare access, healthcare prices, and the delivery of care for specific diseases. Unfortunately, these studies use different, and sometimes conflicting, measures of scope of practice laws, limiting their comparability and overall usefulness to policymakers and future researchers. We address this salient problem by providing a consistent coding of nurse practitioner scope of practice laws over a 23-year period based on actual statutory and regulatory language. Our classification of scope of practice laws solves an important problem within this growing literature and provides a solid legal foundation for researchers as they continue to investigate the effects of these laws.