This longitudinal study assessed the contributions of psychosocial factors to symptoms of posttraumatic stress disorder (PTSD) during pregnancy and at 7 and 13 months postpartum in a sample of 206 low-income Latinas receiving prenatal services. Bilingual interviewers administered semistructured interviews that assessed sociodemographic characteristics (income, age, marital status, acculturation) and psychosocial factors (intimate partner violence (IPV), other lifetime trauma, depressive symptoms, and social support). Hierarchical linear regression analyses were conducted at each of the 3 time points in pregnancy and postpartum to identify the best predictors of PTSD symptoms. Results revealed that low-income, depressive symptoms and a history of other lifetime trauma were associated with symptoms of PTSD during pregnancy. After controlling for PTSD symptoms at baseline, PTSD symptoms at 7 months postpartum were associated with depressive symptoms, low perceived social support, and IPV history, but not history of other trauma. After controlling for PTSD symptoms at 7 months postpartum, PTSD symptoms at 13 months were associated with depressive symptoms and IPV. Screening for depressive symptoms and noninterpersonal trauma history in early pregnancy and for depressive symptoms, IPV, and social support postpartum in low-income Latina women may aid in identifying those at heightened risk for mental distress.