Postpartum depression (PPD) has serious effects on maternal and infant morbidity and mortality. This study aimed to determine the prevalence of postpartum depression in mothers of under-twos in military barracks in Lagos. The Edinburgh Postnatal Depression Scale (EPDS) and a modified version of the General Help-Seeking questionnaire (GHSQ) were administered to 316 mothers of under-twos in 3 of 12 military barracks in Lagos, Nigeria to determine PPD and major depressive events (MDE). Risk of PPD was established at EPDS scores of >12. Good help-seeking practices were ascribed to scores of 20 or more on the GHSQ. Risk of PPD was found in 15.5% of respondents, and good help-seeking in 3.8% and 11.4% for personal/emotional and harming self/baby respectively. Bivariate analysis using Chi square showed statistically significant positive associations between lower scores for EPDS and higher educational levels of respondents, perception of partner support and being in lower wealth quintiles (p<0.05). Use of the EPDS was accepted among mothers of children aged under two years. Opportunities to educate pregnant women and new mothers about PPD using existing social networks, perinatal and infant screening programmes in the barracks can be leveraged upon to improve mental health delivery as part of maternity care.