This paper presents a systematic discussion regarding the Association of Boards of Certification in the Environmental Occupations (ABC) and Reciprocity, including what, why and how the ABC programs are utilized. Certification, ABC, and Reciprocity are defined. The Board of Certification and Registration is described and the Uniform Program for Reciprocity including the Reciprocity Partners program and the Reciprocity Register programs under its guidance are explained. After defining and describing the above, the rationale and justification for the program existence are presented. The paper concludes with a brief discussion of the ABC reciprocity application process.