Green and Gerber are pioneers in the use of experimental design to investigate voter turnout. When the first edition of Get Out the Vote came out 20 years ago, it stood alone in the field of political campaigning for both focusing on get out the vote (GOTV) and basing its recommendations on scientific evidence. The fifth edition incorporates the breadth of similar research that has been conducted in the intervening years. In particular, it includes new ways organizers use technology and new findings on relational organizing. Previously, campaigns relied heavily on generic mailings and prerecorded phone messages to increase turnout; however, the evidence indicates mass appeals are ineffective. Rather, a personal interaction with an acquaintance is much more likely to prompt voters to go to the polls. The book carefully lays out the research leading to that conclusion, and in the process it illustrates how experiments can be conducted in the field to verify the effectiveness of new GOTV techniques. This book provides essential background for students and practitioners of political campaigning. Essential. General readers through faculty; professionals.