This study analyzes the impact of mental health problems and mental health treatment on low-income mothers' employment, using the 2002 National Survey of America's Families. We find that all mothers, low-income mothers, and low-income single mothers in very poor mental health are significantly less likely to work. Instrumental variables regressions show that mothers receiving mental health treatment are significantly more likely to work. These findings suggest that mental health problems are an important barrier to work among low-income women and that access to treatment for these problems can substantially improve the probability of work for this group.