Drawing insights from nearly a decade of mixed-method research, Stephen R. Barnard analyzes Twitter’s role in the transformation of American journalism. As the work of media professionals grows increasingly hybrid, Twitter has become an essential space where information is shared, reporting methods tested, and power contested. In addition to spelling opportunity for citizen media activism, the normalization of digital communication adds new channels of influence for traditional thought leaders, posing notable challenges for the future of journalism and democracy. In his analyses of Twitter practices around newsworthy events—including the Boston Marathon bombing, protests in Ferguson, Missouri, and the election of Donald Trump—Barnard brings together conceptual and theoretical lenses from multiple academic disciplines, bridging sociology, journalism, communication, media studies, science and technology studies, and political science.