OBJECTIVE: To study the prevalence of, severity of, and risk factors for depressive symptoms in a probabilistic sample of Mexican adolescent mothers. METHODS: A sample of adolescents aged 13-19 years, drawn from a national survey, was interviewed in relation to severity of depressive symptoms [Center for Epidemiological Studies Depression Scale (CES-D) 16-23 and CES-D > 24] and pregnancy or parenting status. RESULTS: Depressive symptoms (CES-D 16-23) ranged from 2.3% in the first postpartum semester to 32.5% in the second trimester of pregnancy; high depressive symptoms (CES-D > 24) ranged from 3.0% in the second postpartum semester to 24.7% in mothers of an infant more than 1 year old. Significant differences between groups were in mothers in the second gestation trimester, who had significantly more symptoms than those who had never been pregnant and those in the first postpartum semester. In those with high symptomatology, no significant differences were observed between groups. A multinomial logistic regression model used to estimate the likelihood of depression found increased risk of depressive symptoms (CES-D 16-23) in those without a partner in the first, second, or third trimester of pregnancy; in the second postpartum semester; and with a child over the age of 1 year. Increased risk of high symptomatology (CES-D > 24) was found in those not in school or with a child over the age of 1 year. CONCLUSIONS: Depressive symptoms entail an enormous burden of disease for the mother and mental health risks to the infant; mothers should therefore be targeted in prevention and intervention actions.