A peer-based intervention is a consultative and participatory process in which a group of people selected from a specific population – in this case, people deprived of their liberty – express their health concerns freely, reflect on them and get help to find adequate solutions. The general objective of peer-based interventions in places of detention is to promote the health and well-being of people deprived of their liberty. Most of the ICRC’s current health-related activities in detention are related to curative care; health promotion receives less attention. Health promotion in places of detention will become a matter of priority in upcoming years. The approach proposed in this document is an opportunity to enable the ICRC, even more than before, to put people deprived of their liberty at the centre of its detention-related activities.