During presidential elections a quadrennial debate emerges, wherein candidates lay claim to qualification for the presidency based on their prior professional experiences. Usually this entails invoking the legacy of one of the great presidents, who followed the same trajectory to the White House. Missing from this debate is a systematic analysis of how the different job experiences prepared the population of all presidents for service. For each of the greats who followed a particular pathway to the presidency there is at least one failure who shared the pathway. This book takes both a quantitative and descriptive approach to evaluate all the presidents systematically in order to discuss how prior professional experiences influence presidential performances.