Objective: The present study aimed to investigate weight retention and body composition in the postpartum period between adolescent girls and older women. Design: A prospective cohort study. Anthropometry and skinfold thickness measurements were performed at the first antenatal visit and at 6 weeks postpartum. An FFQ was administered at 6 weeks postpartum to explore the relationship between diet and postpartum weight retention. Setting: Clinics at the University of the West Indies, Kingston, Jamaica. Subjects: Recruitment included women aged 19 years and younger (adolescent girls) and 20 years and older (older women). Results: Three hundred and forty women were studied. Adolescent girls had significantly lower measurements compared with the older women at the first antenatal visit and at 6 weeks postpartum. Dietary intakes of energy and macronutrients were similar in both groups. Postnatal assessments showed that adolescent girls retained more weight (P 5 0?003) and a greater percentage of body fat (P , 0?002) than older women. In multiple regression analyses, 0?982 kg more fat mass was retained postpartum in the adolescent group compared with the older women, while there was no significant difference in lean body mass retained between the two groups. Conclusions: Adolescent girls retained more weight postpartum and this was predominantly fat mass as opposed to lean body mass.