This book began by asking what factors account for wealth accumulation and mobility. That is, why do some people get rich while others never seem to get ahead. Wealth is the things people own, including their homes, savings, investments, other real estate, businesses, and vehicles. Recent shifts in economic conditions propelled some people to great wealth and ignited interest in how this process unfolds. Subsequent economic downturns highlighted the fact that wealth can be – and often is – fleeting. Researchers have been more interested in wealth in recent years, perhaps than at any other point in history. We now have many excellent sources of information about household asset and debt ownership, and this has allowed us to specify very precisely the nature of wealth distribution. That is, we know a great deal about how wealth ownership is allocated across people: what percentage of the total pie is owned by what percentage of the population. The bottom line is that a very small percentage of Americans owns the vast majority of wealth. Yet even with this increased interest in wealth and our improving ability to understand wealth, we know very little about the process by which people accumulate assets. What is it about their backgrounds and the paths they follow through their lives that makes some people accumulate lots of assets while others never seem to save much of anything? Is it simply that those who start off with more end with more?