The rise in divorce, cohabitation, single parenthood, and same-sex partnerships, along with an increase in surrogacy, adoption, and assisted reproductive technologies, has led to many diverse configurations of families, or intimate associations. J. Herbie DiFonzo and Ruth C. Stern chart these trends over the past several decades and investigate their social, legal, and economic implications.

Drawing upon a wealth of social science data, they show that, by a number of measures, children of married parents fare better than children in a household formed by cohabiting adults. This is...