A small collection of well-honed tools has been employed for some time by media practitioners and the public to help maintain and improve the credibility of journalism and the mass media. These media accountability tools have included ethics codes, media critics, news councils, ombudsmen, journalism reviews and pubic/civic journalism initiatives. Now, in the 21st Century, the mass media are increasingly being buffeted by a perfect storm of declining subscribers and audience share, dwindling advertising revenue, changing corporate demands, unpredictable audiences and new-media competition. If journalism and the mass media are to stay afloat and be credible, the media accountability toolbox needs to contain suitable tools for the job, which begs the question: Who will Watch the Watchdog in the Twitter Age? This book contains answers to this question from the perspective of 17 media ethics experts from around the globe. Their answers will help shape and define for years to come the tools in the media ethics toolbox. This book was originally published as a special issue of the Journal of Mass Media Ethics.