This article proposes a conceptual framework to explain the adoption and diffusion of a national human resource development (NHRD) standard. NHRD standards are used by governments to promote training and development in organizations and increase the professionalization of practices used by organizations. Institutional theory suggests that adoption and diffusion of HRD practices can be explained using a number of institutional concepts such as structural equivalence, social cohesion, and normative and mimetic isomorphism. Social cohesion and structural equivalence create normative and mimetic pressure, which results in increased adoption and diffusion. We highlight other organizational characteristics that explain adoption and diffusion, and also the implications for both theory and research. (Contains 1 figure.)