The Safety Management System (SMS) is a new management practice used in addition to the current prescriptive regulatory approaches. This study aims to find out, from the perspective of the new institutional theory, the diffusion of the SMS among the aviation organizations. Deductive and inductive methods were used together for the analyses of the qualitative data. The research shows that what lies beneath the diffusion of SMS is regulative institutional pressure, and that the field is dominated by coercive isomorphism mechanisms and a concern for legitimacy. Furthermore, it is found that the majority of organizations that participated in this study had recourse to decoupling strategies in SMS and adopted SMS practices only in a ceremonial way.