Abstract: The Behavior Analyst Certification Board (BACB) has been certifying and developing professional standards for behavior analysts since it emerged in 1999 from the state of Floridaï¿½s behavior analyst certification program, which had been in operation for two decades earlier. In 2007, the BACBï¿½s Board Certified Behavior Analyst (BCBA) and Board Certified Assistant Behavior Analyst (BCaBA) credentials were accredited by the National Commission for Certifying Agencies (NCCA). The NCCA accredits certification programs that adhere to the best practices of the credentialing and testing industries, including highly prescribed procedures for establishing and revising key standards. In this presentation, I will describe the evolution of certification standards in behavior analysis over the decades, including the systematic NCCA-mandated procedures the BACB has followed to develop and revise its standards over the years. This process has been akin to shaping and has allowed behavior analyst certification to grow and flourish alongside consistently increasing standards towards an eventual steady state. Special focus will be paid to standards where the steady state appears to have been reached. Finally, I will describe how BACB certification standards align with the licensure of behavior analysts in approximately two dozen US states.