Although the basic facts about wealth inequality are no longer a mystery, we still know very little about who the wealthy are, how they got there, and what prevents other people from becoming rich. That is, we know very little about the process of wealth mobility. This book investigates some of the most basic questions about wealth mobility. The advantages of owning wealth and the elusive nature of true wealth have long made questions about the wealthy broadly appealing. In recent years, that interest has been amplified by dramatic economic changes and rising wealth inequality.