The stability of many post-conflict societies rests on the successful reintegration of former soldiers. We use a set of behavioural experiments to study the effects of forced military service for a rebel group (the Lord's Resistance Army) on trust and trustworthiness in Northern Uganda. We present evidence that soldiers did not self-select nor were systematically screened by rebels. We find that the experience of soldiering increases individual trustworthiness and community engagement, especially among those who soldiered during early age. These results suggest that the impact of child soldiering on social behaviour is not necessarily detrimental.