The media environment is changing. Today in the United States, the average viewer can choose from hundreds of channels, including several twenty-four hour news channels. News is on cell phones, on iPods, and online; it has become a ubiquitous and unavoidable reality in modern society. The purpose of this book is to examine systematically, how these differences in access and form of media affect political behaviour. Using experiments and new survey data, it shows how changes in the media environment reverberate through the political system, affecting news exposure, political learning, turnout, and voting behavior.