The need for a credible professional credential became apparent early in the history of applied behavior analysis. The first efforts to develop a system that identified behavior-analytic practitioners having a specified level of expertise in the profession began in the early 1970s. Over the years, a number of credentialing initiatives were developed in an effort to meet the profession's growing needs for a means of establishing a meaningful professional identity. This article reviews the evolution of these initiatives, culminating with the Behavior Analyst Certification Board and the more recent movement toward state licensure.