Summary Objective To evaluate the provision of psychosocial interventions of potential benefit to pregnant teenage women. Study design Pre-test/post-test, controlled, experimental design. Methods One hundred and sixty-four pregnant teenage women received usual midwifery care or usual midwifery care plus additional psychosocial support. Four outcomes were measured at baseline and 4 weeks after delivery: self-esteem (Rosenberg Self-Esteem Scale), physical activity (International Physical Activity Questionnaire), social support (Short Form Social Support Questionnaire) and smoking behaviour (yes/no). Results At follow-up, there were no significant differences in any of these outcomes between the 65 women in the intervention group and the 64 women in the control group who completed both assessments (mean age 17.5 years). There was no difference in use of National Health Service (NHS) services, but the intervention group made greater use of non-NHS services, such as family planning or help with housing or benefits problems. Conclusion The very low self-esteem of the women in the study may indicate that the intervention was not sufficiently robust to impact on mental health and lifestyle, although a longer follow-up may be needed to confirm this. Discrepancy in the evidence provided by formal and informal data suggests that project benefits may have been more evident if the evaluation had included a qualitative element to address the complexity of the client group and intervention.