Postpartum depression (PPD) affects 10%-15% of mothers within the first year after giving birth. Younger mothers and those experiencing partner-related stress or physical abuse might be more likely to develop PPD. CDC analyzed data from the Pregnancy Risk Assessment Monitoring System (PRAMS) for 2004-2005 (the most recent data available) to 1) assess the prevalence of self-reported postpartum depressive symptoms (PDS) among mothers by selected demographic characteristics and other possible risk factors for PDS and 2) determine factors that identify mothers most likely to develop PPD. This report summarizes the results of that analysis, which indicated that, during 2004-2005, the prevalence of self-reported PDS in 17 U.S. states ranged from 11.7% (Maine) to 20.4% (New Mexico). Younger women, those with lower educational attainment, and women who received Medicaid benefits for their delivery were more likely to report PDS. State and local health departments should evaluate the effectiveness of targeting mental health services to these mothers and incorporating messages about PPD into existing programs (e.g., domestic violence services) for women at higher risk.