Between 1970 and 1988, the number of single parents with children under 18 in the home more than doubled from 3.8 million to 9.4 million. This dramatic rise is reflected in the increase of single-parent families as a proportion of all family groups with children: from 13 percent in 1970 to 27 percent in 1988. This increase is one of the most important recent changes in family composition, with major implications for poverty and social welfare programs.

The total number of single parents is made up of those who maintained their own households with their children under 18 (families) and those who lived in someone else's household with their children (subfamilies); about 1 of 5 single parents lived in someone else's household.