Family law is based on marriage, but family life increasingly is not. The American family is undergoing a seismic shift, with marriage rates steadily declining and more than four in ten children now born to unmarried parents. Children of unmarried parents fall far behind children of married parents on a variety of metrics, contributing to stark inequality among children. Poverty and related factors explain much of this differential, but new sociological evidence highlights family structure — particularly friction and dislocation between unmarried parents after their relationship ends — as a crucial part of the problem. As the trend toward nonmarital childbearing continues to spread across class lines, the effect will be most pronounced amon...