While a peace agreement between the Revolutionary Armed Forces of Colombia (FARC) and the Colombian government seems to be within reach, a number of substantial and procedural issues might still cause controversies. One such topic is the question of how a potential peace agreement should be ratified. Both parties have made clear that ratification should involve direct citizen participation. The FARC’s proposal for a broadly mandated Constituent Assembly is effectively not politically viable. Other constitutional options have practical, political and legal implications. A final formula will need to deal with the armed group’s concern for the legal security of its members while rapidly generating a political mandate to proceed with implementation. The inevitable time lag between signature and ratification will most certainly become a political liability because the FARC is likely to refuse to lay down its weapons in this period. With low levels of trust between the parties and a society deeply sceptical of the guerrilla’s intentions to abandon the armed struggle, all sides will feel the need to be protected against risks of non-compliance. The greatest risk related to citizen ratification remains non-approval, because large parts of the population continue to be sensitive – if not opposed – to the idea of granting wide-ranging concessions to the FARC. Mobilising a strong political and social majority behind the peace process and a potential deal is a priority if a final agreement is to survive popular scrutiny and become a foundation for lasting peace.