Mechanisms for credentialing affecting occupational health nursing include licensure and certification of individuals and accreditation of educational and health care organizations. 2. Issues of control of entry into practice, geographic mobility, and whether licensure will be single or two tiered, national or institutional, are currently under debate. 3. The purpose of certification is to acknowledge the individual and assure the public that the individual has mastered a body of knowledge of a particular specialty. 4. The purpose of accreditation is to evaluate the performance of a service (i.e., education or health care) and to provide consumers of that service necessary information on which to base decisions on use of the services. 5. Occupational health nurses must participate actively in the process of credentialing clarification and reform to be prepared to advance the specialty and respond to the health care needs of the working population in the 21st century.