McCombs is internationally recognized for his research on the agenda-setting role of mass communication. Since the original Chapel Hill study with his colleague Donald Shaw coined the term "agenda setting" in 1968, more than 400 studies of agenda setting have been conducted worldwide.
The agenda setting role of media in presidential elections, political communication, media, the role of social media (blogs, YouTube, MySpace, Facebook, Twitter) in political communication.
McCombs also spent 10 years as director of the News Research Center of the American Newspaper Publishers Association.
"Setting the Agenda: The Mass Media and Public Opinion" (2004 Polity Press)