Oren Cass explains for National Review Online readers why social inequality matters more than income inequality.

By one measure, opportunity and mobility are thriving in America. Children born into the lowest income quintile have almost exactly equal chances of arriving in any of the five income quintiles as adults. There is only one catch: Their parents must be and stay married. Children whose parents never marry face poor prospects: More than half remain in the bottom quintile, ten times the share that reaches the top.

Tragically, this latter scenario is becoming the norm. America’s “lower class,” for lack of a better term, is undergoing an unprecedented social collapse that threatens to destabilize core American principles. The data on marriage, parenting, employment, civic engagement, and basic values show a widening and sometimes accelerating gap between classes. This form of inequality is far more consequential than income inequality because strong families and communities, unlike high incomes, are the cornerstones of a free and fair society.

Being raised very poor does not cut off opportunity, but what about being very poorly raised?

Today’s correlation between poverty and a host of social ills has led policymakers to treat them almost interchangeably and emphasize economic relief. But the correlation is historically anomalous: Fifty years ago, though poverty was no less prevalent, class-based gaps on social indicators from marriage to child-rearing to labor-force participation were small to nonexistent. This suggests that today’s emphasis on economic resources is a mistake. Rather, the focus should be on disrupting the cycle of poverty in which social decay in one generation inhibits the development of the next, individuals ill-prepared for life and work face limited opportunity, and their ensuing struggles cause further social decay.