Abstract This paper reveals how negotiators, from the police and emergency call centres, overcome resistance towards the negotiation from suicidal persons in crisis. Communication guidance to hostage and crisis negotiators recommends against challenging the person in crisis, focusing instead on a softer, rapportful approach. Using conversation analysis, we investigate how negotiators deal with resistance, turn by turn, in encounters collected from British police negotiators’ field recordings, and American police 9-1-1 dispatch telephone calls. In contrast to existing communication guidance, we show that and how challenges can be productive for bringing about positive shifts in suicidal persons’ behaviour. We demonstrate how negotiators challenge the reasoning in their interlocutors’ resistant responses and leverage these challenges productively in the next turn. By studying real (rather than hypothetical or simulated) negotiations, the study reveals the tacit expertise of negotiators and the communicative practices that optimize negotiation outcomes. These research findings have significant implications for existing communication guidance showing how negotiations are managed locally through the linguistic design of turns of talk.