The purpose of credentialing is to assure the public that individuals who practice an occupation or profession 1 have met certain standards (American Educational Research Association [AERA], American Psychological Association [APA], & National Council on Measurement in Education [NCME], 1999). The two most common forms of credentialing are licensure and certification. Licensure is the "process by which an agency of the government grants permission to an individual to engage in a given occupation" (U.S. Department of Health, Education, and Welfare, Public Health Services, 1977, p. 4). Licensure laws define the scope of activities a licensed individual may perform and those activities that an unlicensed individual is prohibited from performing. The purpose of licensure is to protect the public from unqualified practitioners. In contrast, certification usually refers to the process by which an organization grants recognition to an individual who has voluntarily met the requirements established or adopted by the granting organization (Shimberg, 1981(Shimberg, , 1982. Individuals who meet the stated requirements are issued a credential, such as Certified Emergency Nurse (CEN) or Cisco Certified Network Professional (CCNP).The classic distinction between licensure and certification is that licensure is mandated by law with the intent of controlling what a person can and cannot do, whereas certification is often voluntary and regulates the title a person uses. This distinction 1 The Standards for Educational and Psychological Testing and other publications use the term credentialing to refer to both licensure and certification. This chapter follows that convention except in cases in which the distinction is important. Also, the term profession as used in this chapter refers to occupation, trade, or profession.