Abstract Unlike the European and African systems, the Inter-American human rights system entirely excludes the participation of interested third parties in proceedings before its judicial body, the Inter-American Court of Human Rights. This article argues that the reasons typically given to justify this exclusion are insufficient —at least on their own— to fully justify the exclusion of third-party interventions. Furthermore, the article contends that this exclusion poses challenges to both due process and the institutional capacities of the Court, particularly in a context where the Court is tasked with addressing highly polycentric problems. The article suggests re-evaluating the exclusion of interested third parties, which should lead to a reform of the Court’s Rules of Procedure. Finally, it explains that this proposal is consistent with certain trends developed by the Court in recent years.