This paper analyses a previously unexamined but nonetheless important facet of modern society the nature and impact of the relationship between in-house tax professionals in large multinational organizations, and the external business, tax and regulatory environments within which they operate. Drawing on face-to-face interviews conducted with senior tax executives in US multinational enterprises (MNEs), we uncover the social reality of the world in which MNEs' tax executives operate, and find that these tax professionals are a powerful, elite group of knowledge experts who can significantly shape tax law and practices. We analyze the activities of these experts who, although working largely in. the shadows of their organizations, are very much engaged in constructing and shaping the wider institutional environment. From a theoretical perspective that brings together institutional work and the endogeneity of law, we find these elite professionals engaging in subtle and diffuse exercise of power at a micro level within their organizations, a meso level between organizations within the field and at a macro level within the wider external environment. This has important implications for our broader understanding of the tax and regulatory environments which corporate actors inhabit. (C) 2015 Elsevier Ltd. All rights reserved.