The purpose of this study of mid-life and older women was to assess the relation between informal care provision and depressive symptoms, taking into account concurrent demands on women's time (including multiple caregiving roles and employment outside the home) as well as participants' access to potentially supportive social ties. This cross-sectional study included women ages 46-71, free from major disease, who provided complete health and social information in the 1992 Nurses' Health Study follow-up survey (n = 61,383). In logistic regression models predicting depressive symptoms, we examined the interaction between employment outside the home and informal care provision for a disabled or ill spouse or parent. We also investigated level of social ties, measured with the Berkman-Syme Social Network Index, as a potential modifier of the association between informal care provision and depressive symptoms. In all analyses, higher weekly time commitment to informal care for a spouse or parent was associated with increased risk of depressive symptoms. This relationship persisted whether women were not employed outside the home, were employed full-time, or were employed part-time. Higher weekly time commitment to informal care provision was associated with increased risk of depressive symptoms whether women were socially integrated or socially isolated. However, both informal care provision and social ties were potent independent correlates of depressive symptoms. Therefore, women who reported high spousal care time commitment and few social ties experienced a dramatic elevation in depressive symptoms, compared to women with no spousal care responsibilities and many social ties (OR for depressive symptoms=11.8; 95% CI 4.8, 28.9). We observed the same pattern among socially isolated women who cared for their parent(s) many hours per week, but the association was not as strong (OR for depressive symptoms=6.5; 95% CI 3.4, 12.7). In this cross-sectional study, employment status did not seem to confer additional mental health risk or benefit to informal caregivers, while access to extensive social ties was associated with more favorable caregiver health outcomes.