This chapter looks at the persuasion strategies and successes of INGOs. Building on the theoretical framework of Chapter 2, we examine to what extent the most capable INGOs engage in conflict warning (warner capacity), when and how they communicate warnings (communication and message factors) and how they are perceived by key recipients in media and policy-making (credibility and persuasiveness). Our investigation centres on Amnesty International, Human Rights Watch and the International Crisis Group. These INGOs are atypical insofar as they belong to a small group of international ‘advocacy superpowers’. We draw on three sources of data: first, interviews with 154 practitioners from international and local NGOs and think-tanks plus a further 127 interviews with foreign affairs journalists and government/IO officials in the field of conflict prevention; second, a text analysis of the public warning output of these NGOs across six different conflict cases; and third, a recipient survey among analysts and officials active in different organisational contexts, most notably the EU, the United Kingdom and the UN.