Although several longitudinal studies have demonstrated that having a disadvantaged family background is a risk factor for subsequent symptoms of depression, few studies have examined the mediating mechanisms that explain this long-term relationship. Thus, this study uses US national longitudinal data and integrates social stress theory with the life course perspective by focusing on two mediating mechanisms—the chronic stress of poverty and self-esteem during the transition to adulthood. Results reveal that self-esteem largely mediates the inverse relationship between parental education and levels of depressive symptoms in young adulthood. However, the inverse relationship between parental occupational prestige and depressive symptoms among young adults is not mediated by self-esteem, but rather long durations of poverty across 16 years. Overall, these findings suggest that different components of family socioeconomic status can leave a lasting imprint on mental health via the self-concept and the chronic stress of poverty throughout the journey to adulthood. Copyright © 2013 John Wiley & Sons, Ltd.