In 1991, the Government Accounting Office (GAO) developed an empirical estimate of the magnitude of the problems mother-only families face in escaping poverty. The GAO also tried to identify federal policies that could help such families. Data from the National Longitudinal Survey of the Labor Market Experience of Youth were used to assess the expected earnings of single mothers working full- or part-time, the availability of sick leave and health insurance, and child care problems. Potential earnings and other reported sources of income were compared with the poverty line to see whether single mothers could be expected to support themselves without public assistance. The study found that many single mothers will remain near or below the poverty line even if they have full-time jobs. Problems they are likely to face include low earnings; vulnerability to layoffs and other work interruptions; lack of such benefits as paid sick leave and health insurance; and relatively high expenses for child care. The 1990 legislative expansion of the earned income tax credit and child care subsidies could increase the percentage of poor families that live without welfare. Nevertheless, many poor single mothers will still need better job skills to raise their earnings. Otherwise, public assistance, especially Aid to Families with Dependent Children benefits, food stamps, and child support payments, will be necessary if these mothers are to live above the poverty line. Appendixes detail: (1) the wage-earning potential of, and hours worked by, single mothers; (2) the availability of fringe benefits; and (3) calculations of potential AFDC benefits for employed single mothers in various states. (AC)