This paper reviews the large literature on family change. Ultimately we want to know how well social scientists really can explain the intertemporal changes in the prevalence of single parent families, particularly the variations across groups. We also want to identify places we might look for further answers. To do this we will need to look not just at work dealing with single parenthood per se but at work dealing with its proximate causes: the rise in out of wedlock childbearing and divorce, the decline in marriage rates among those who are already single parents, and the fact that less educated women have postponed marriage far more than they have postponed childbearing. Our review suggests that while many questions remain unanswered, social scientists may have learned more than they realize. It also suggests that more progress can be made by looking at marriage and fertility simultaneously, and by integrating economic and cultural theories.