The American Association of Occupational Health Nurses (AAOHN) promotes occupational health nursing by participating in national and state deliberations on credentialing issues. In 1995, AAOHN established the Credentialing Ad Hoc Committee to examine the impact of credentialing on occupational health nursing practice. As one effort by this Committee to clarify credentialing and the issues affecting the occupational health nurse, a series of three articles will appear in AAOHN Journal. This article defines credentialing and describes some of the issues affecting occupational health nursing. The second article will be based on the 1997 American Occupational Health Conference, Catherine Dempsey lecture elaborating on the future of credentialing in occupational health nursing. The final article will present the results of a national project conducted in 1996 asking AAOHN members for input in determining levels of competency in occupational health nursing practice.