Legitimation and competition are two major forces moulding organizational field and the diffusion of innovations. While discursive legitimation provides "rational justifications" for innovations, competition may incite organizations to acquire effective innovations preemptively. This paper draws on a case study of the legitimation and diffusion of a sophisticated medical technology to suggest that, in highly regulated environments, these two forces may interact, and that opposing legitimation strategies may be associated with competition. We argue that while convergent discursive legitimation strategies tend to speed up the diffusion process, divergent discursive legitimation strategies may have the opposite effect. The case suggests that the dominant logics of legitimation may shift, oscillating between convergence and divergence as an innovation diffuses. We also show how the resulting delays in diffusion may be pre-empted by a phenomenon we call institutional delinquency, that is when the moral and cognitive-cultural legitimacies of the technology among professionals and managers becomes sufficient to counteract regulatory forces. [Authors]