The increasing labor supply of single mothers in the US labor market in the 1990s is well documented, but due to data deficiencies it generally has been difficult to track the progress in the labor market of this group. In this study we integrate household characteristics data from the Current Population Survey with administrative longitudinal employment and earnings records from the US Census Bureau's Longitudinal Employer-Household Dynamics (LEHD) program, enabling us to construct employment and earnings histories covering the six years prior to and five years following the survey year (either 1997 or 1998) of each respondent. In contrast to the broader population, single mothers as a group had persistently lower rates of employment and, if employed, higher job volatility and stagnant earnings in the years prior to the survey year. Subsequently, their position in the labor market improved markedly: low-income single mothers, in particular, experienced relatively rapid earnings growth and increased employment stability. Even so relatively large fractions of low-income single mothers continued to experience difficulties in the labor market, and a more detailed analysis of the factors contributing to success in the labor market suggests that past employment histories are closely related to subsequent labor market outcomes.