Campaign strategists and political scientists studied how to nudge people to vote for more than a century. The strategists have concentrated on nudging (and shoving) people to vote for a particular candidate. The political scientists, trying to stay detached from partisanship, have studied how to nudge people to fulfill their civic duty go to the polls on election day. In the last few years the cutting edge of political science research on voter mobilization has involved a method known as a field experiment. Originally pioneered in the 1920s and recently re-pioneered by Alan Gerber and Don Green at Yale, field experiments involve randomly sending letters, airing radio and print advertisements, phoning homes, or sending canvassers door-to-door making personal pitches. The random assignment of these various forms of voter outreach is the crucial piece of field experiments – call it the “magic” – that enables researchers to calculate clean estimates for how much these nudges affect voter decisions.