The purpose of this study was to examine the role of self-esteem as a mediator of the effects of stressors and social resources on mothers' postpartum depressive symptoms. Data were collected during in-home interviews with 738 women 1 to 2 months postpartum. Forty-two percent of the women had high depressive symptoms. Self-esteem mediated the effects of everyday stressors and the quality of primary intimate relationships on depressive symptoms. However, everyday stressors also exhibited direct effects. Mothers with low self-esteem were 39 times more likely to have high depressive symptoms than those with high self-esteem. Interventions to decrease postpartum mothers' chronic stressors and to improve the quality of their primary intimate relationships may enhance their self-esteem, which in turn may decrease the likelihood of high depressive symptoms.