The importance of journalism to civil society is constantly proclaimed, but empirical evidence on journalism's impact, and how this operates, is surprisingly thin. Indeed, there is confusion even about what is meant by the term "impact". Meanwhile, the issue of the role of journalism is becoming increasingly urgent as a consequence of the rapid changes engulfing the news media, brought about by technological change and the flow-on effect to the traditional advertising-supported business model. Assessing the impact of journalism has recently been the topic of debate among practitioners and scholars particularly in the United States, where philanthropists have responded to the perceived crisis in investigative journalism by funding not-for-profit newsrooms, with resulting new pressures being placed on journalists and editors to quantify their impact on society. These recent attempts have so far failed to achieve clarity or a satisfactory conclusion, which is not surprising given the complex web of causation within which journalism operates. In this paper, the authors propose a stratified definition of journalistic impact and function. They propose a methodology for studying impact drawing on realistic evaluation—a theory-based approach developed primarily to assess large social programmes occurring in open systems. The authors argue this could allow a conceptual and methodological advance on the question of media impacts, leading to research capable of usefully informing responses at a time of worrying change.