The American vice presidency has become an office of major political importance. Consequently, the question of how the vice presidents are chosen should be of great current interest. However, scholarly attention devoted to this subject has been scarce. There are posited only three distinct theories on the mechanisms governing the selections of vice presidents. This book seeks to expand on that theoretical framework. It tests the explanatory powers of the existing theories statistically, through a conditional logistic regression analysis. Thus, it identifies the factors that best explain the vice presidential selections from 1940 to 2008. The book is therefore an interesting read for students of political science, the American government or simply anyone that has ever wondered why presidents choose the running mates they do.