One of the most surprising and controversial social debates of the past two decades has been about the meaning and importance of marriage and the family in contemporary American life. Referred to by some as a culture ‘war over the family, ‘ the debate has pitted those concerned about the weakening of the traditional married-parent nuclear family, especially in its impact on children, against those arguing that nothing has gone wrong with families—that they are merely ‘diversifying.’ David Popenoe has been one of the most influential figures in laying out for a wide audience the importance of ‘family decline, ‘ and what it means for our children, our society, and our future.