Some managerial innovations (MIs) spread widely, and others do not. To gain a better understanding of why, the current empirical study offers a rare qualitative exploration of the interplay of two approaches to MI diffusion : rational and institutional. Using a case study of the emergent MI of mindfulness-based interventions at work, the authors show that, of the many attributes traditionally cited to explain MI diffusion, those pertaining to compatibility and a capacity to be adapted are key. “Fashion setters” (in an institutional approach) and “change agents” such as consultants and gurus (in a rational approach) are often identified as key players in MI diffusion. However, the current study challenges this assessment by offering more nuanced insights. In particular, the influence of such agents decreases if they do not find relays within companies that have adopted MIs early. Furthermore, other actors can emerge as opinion leaders in the shadows.