The dangerous spiralling of the rivalry between the Kingdom of Saudi Arabia and the Islamic Republic of Iran for hegemony/supremacy in the Middle East/Gulf is the factor that has the most negative impact on the entire region. The authors make the case for using the specific features and successful negotiations of the historic Joint Comprehensive Plan of Action (JCPOA) as a way to downgrade this bilateral rivalry. This agreement was the focal point of (pre-)negotiations especially between the United States and Iran that de-escalated the tensions between the two enemies and turned them – at least during the administration of President Barack Obama – into adversaries with an interest in selective cooperation. The agreement is living proof that formerly incompatible interests can be overcome. It is true, however, that, despite its complexity, the JCPOA can only have a limited influence on developments in the region. This is why the authors identify the roots of the intensifying Saudi Iranian rivalry at the domestic, regional and international levels – with corresponding recommended steps to de-escalate this struggle. The prospects for such a positive scenario appear to be particularly promising if elites in both Riyadh and Tehran – especially since they are facing increasing domestic challenges to regime/government stability – opt to slow down or even reverse their countries’ current course. A more assertive population, especially among women and the youth, has become a new factor for serious change. This may incentivise these elites to pursue less costly foreign policy approaches – including finding appropriate forums for serious dialogue, with de-escalating the mutually demonising rhetoric as the first step.