Data on marital status are used to produce statistics on marriage and divorce, as well as to provide information on the characteristics of America's families. As cohabition has become increasingly common and accepted in the United States, statistical agencies face an increased need to gather data on cohabition as well as marital status in order to get a more complete picture of family structure. Statistics on unwed births often include cases where biological parents are unmarried, but cohabiting and planning to raise the child together. Cohabiting couples with children often function much like families that have married parents, but are often categorized as single parents in statistical analyses. Additionally, gay and lesbian couples with children also often fuction as family units, without being married. These households may look like single parent families, with no indication that the child has two parents in the household. Many researchers are interested in the impact of cohabitation on children's well-being. In order to study this, we must be able to identify cohabiting couples with children.