Economic mobility is the ability to get ahead financially. It is the essence of what many mean by the “American Dream”. To be true to our vision of the US as a land of opportunity, someone born to poor parents should have a decent chance of achieving what we think of as a middle-class life. In Part 2 we looked at the data on mobility for countries around the world and found that mobility is similar to our European peers for the middle-class in the US, but that the sons of poor fathers have nearly a fifty percent chance of also being poor as defined by being in the lowest fifth of income. Daughters in the lowest fifth of income do better, about three quarters rise to a higher income group. In short, at both ends of the income spectrum, there is what is called high persistence. Intergenerationally, the poor tend to stay poor, and the well off tend to stay well off. What are the factors that underpin persistent poverty and what can we do about them? We look at that more later.