The objective of this study was to assess the extent to which maternal prenatal mental illness is associated with mothers' health insurance status 12-18 months after giving birth. The sample consisted of 2,956 urban, mostly unwed, mothers who gave birth in 20 large U.S. cities between 1998 and 2000 and participated in the Fragile Families and Child Wellbeing birth cohort study. Multinomial logistic regression models were used to assess associations between maternal prenatal mental illness and whether the mother had private, public, or no insurance one year after the birth. Covariates included the mother's and child's physical health status, the father's physical and mental health status, and numerous other maternal, paternal, and family characteristics. Potential mediating factors were explored. The results showed that mothers with prenatal diagnosed mental illness were almost half as likely as those without mental illness diagnoses to have private insurance (vs. no insurance) one year after the birth. Among mothers who did not have a subsequent pregnancy, those with prenatal mental illness were less likely than those without mental illness diagnoses to have public insurance than to be uninsured. Screening positive for depression or anxiety at one year decreased the likelihood that the mother had either type of insurance. Policies to improve private mental health care coverage and public mental health services among mothers with young children may yield both private and social benefits. Encounters with the health care and social service systems experienced by pregnant and postpartum women present opportunities for connecting mothers to needed mental health services and facilitating their maintenance of health insurance.