Objectives: Depressive symptoms are associated with preterm birth among adults. Pregnant adolescents have high rates of depressive symptoms and low rates of treatment; however, few interventions have targeted this vulnerable group. Objectives are to: (a) examine impact of CenteringPregnancy® Plus group prenatal care on perinatal depressive symptoms compared to individual prenatal care; and (b) determine effects of depressive symptoms on gestational age and preterm birth among pregnant adolescents. Method: This cluster-randomized controlled trial was conducted in 14 community health centers and hospitals in New York City. Clinical sites were randomized to receive standard individual prenatal care (n = 7) or CenteringPregnancy® Plus group prenatal care (n = 7). Pregnant adolescents (ages 14–21, N = 1,135) completed the Center for Epidemiologic Studies Depression Scale during pregnancy (second and third trimesters) and postpartum (6 and 12 months). Gestational age was obtained from medical records, based on ultrasound dating. Intention to treat analyses were used to examine objectives. Results: Adolescents at clinical sites randomized to CenteringPregnancy® Plus experienced greater reductions in perinatal depressive symptoms compared to those at clinical sites randomized to individual care (p = .003). Increased depressive symptoms from second to third pregnancy trimester were associated with shorter gestational age at delivery and preterm birth (<37 weeks gestation). Third trimester depressive symptoms were also associated with shorter gestational age and preterm birth. All p < .05. Conclusions: Pregnant adolescents should be screened for depressive symptoms prior to third trimester. Group prenatal care may be an effective nonpharmacological option for reducing depressive symptoms among perinatal adolescents.