Across a wide range of empirical settings, research on institutional entrepreneurship has focused on how actors are able to successfully create and transform institutional arrangements. Yet few studies have examined why institutional entrepreneurs may fail. This paper examines how audience structure can lead to entrepreneurial failure through a historical analysis of Edmund Berkeley's efforts to legitimize the notion of computers as "Giant Brains." As a prominent early computer expert and institutional entrepreneur, Berkeley occupied a strong structural position within the insurance industry, enjoyed high status, was widely recognized as a leading authority on computers, and possessed plentiful resources. Nevertheless, he foundered in establishing his innovative vision for the computer, especially in his own industry, insurance, because of its centralized audience structure. In manufacturing, on the other hand, a more decentralized audience structure allowed for a partial legitimization of Berkeley's vision.