This book has described the growing political and regulatory scrutiny to which the tax strategies of multinational corporations (MNCs) have been subject in recent years. Despite their growing importance, however, the theoretical or conceptual place of journalists, leakers and whistleblowers in the international anti-avoidance regime remains under-researched. This chapter addresses this gap by describing some of the ways in which whistleblowing and investigative journalism have drawn attention to, and helped to counter, aggressive tax planning strategies. Using survey data and accounting research on the regulatory impact of reputational damage, this chapter evaluates the potential impacts of three regulatory models that have proven effective in other policy arenas. The models discussed are drawn from the environmental protection and corporate governance literature. The chapter argues that, in the case of aggressive tax avoidance, whistleblowers and journalists exercise little effect independently of government, but rather prompt, enable or force further action through official channels.