International organizations are often assumed to be politically influential, but their influence is seldom assessed. This study examined the political influence exerted by the International Plant Genetic Resources Institute (IPGRI) in the international negotiations pertaining to the revision of the International Undertaking for Plant Genetic Resources (1996–2001). The study assessed the level of IPGRI's influence and examined the processes by which IPGRI exerts influence. We obtained evidence from IPGRI staff members who were involved in the negotiations, about the expected ways and means by which IPGRI was thought to have been influential—the so-called “ego-perspective”. Their perceptions were cross-checked against other players’ perceptions of IPGRI's influence (the“alter-perspective”). Finally, the validity of these perceptions was checked through document analysis (“researcher's analysis”). Empirical results relating to IPGRI's political influence were subsequently linked to a theoretical framework. The results indicate that the provision of timely and relevant technical inputs directly linked to IPGRI's area of expertise was the most successful means of influencing the negotiations. Other factors also enabled or constrained IPGRI's ability to influence the negotiations. On one hand, political neutrality and reliability were seen as factors that enhanced IPGRI's ability to influence. However, IPGRI, as any international organization, lacks the resources and formal rights that endow states, and this fact ultimately limited IPGRI's ability to directly influence the negotiations.