Objective: The goal of this study was to characterize racial-ethnic differences in mental health care utilization associated with postpartum depression in a multiethnic cohort of Medicaid recipients. Methods: In a retrospective cohort study, administrative claims data from New Jersey's Medicaid program were obtained for 29,601 women (13,001 whites, 13,416 blacks, and 3,184 Latinas) who delivered babies between July 2004 and October 2007. Racial-ethnic differences were estimated with logistic regression for initiation of antidepressant medication or outpatient mental health visits within six months of delivery, follow-up (a prescription refill or second visit), and continued mental health care (at least three visits or three filled antidepressant prescriptions within 120 days). Results: Nine percent (N=1,120) of white women initiated postpartum mental health care, compared with 4% (N=568) of black women and 5% (N=162) of Latinas. With analyses controlling for clinical factors, the odds of initiating treatment after delivery were significantly (p<.001) lower for blacks (adjusted odds ratio [AOR]=.43) and Latinas (AOR=.59) compared with whites. Among those who initiated treatment, blacks and Latinas were less likely than whites to receive follow-up treatment (blacks, AOR=.66, p<.001; Latinas, AOR=.67, p<.05) or continued care (blacks, AOR=.81, p=.069; Latinas, AOR=.67, p<.05). Among those who initiated antidepressant treatment, black women and Latinas were less likely than whites to refill a prescription. Conclusions: There were significant racial-ethnic differences in depression-related mental health care after delivery. Suboptimal treatment was prevalent among all low-income women in the study. However, racial and ethnic disparities in the initiation and continuation of postpartum depression care were particularly troubling and warrant clinical and policy attention.