This paper analyzes how national institutional factors affect the adoption of the intemational environmental management standard ISO 14001, using a panel of 139 countries from 1996 to 2006. The analysis emphasizes that during the emerging phase of the standard, the potentiallack of consensus within the constituents of the national institutional environment conceming the value of a new standard could send mixed signals to firrns about the standard. The resuIts show that in the early phase of adoption, regulative and norrnative forces within the institutional environment can work against each other. Results also show that regulative or coercive forces playa relatively more important role in the early phase of adoption of the standard than in the subsequent phases of diffusion. In the later phases of diffusion of ISO 14001, norrnative forces, such as the diffusion of other management standards, as well as factors related to trade, playa more important role. Because of the similarities between environmental management standards and corporate social responsibility standards, this study can help identify sorne of the challenges for diffusion of ISO management standards in the area of social responsibility. Publicado