Science-policy interfaces are increasingly being used across the United Nations system to generate, assess and mobilize scientific knowledge for policymakers. This memo examines key considerations for designing these institutions, including lessons from existing interfaces, their ability to adapt to changing circumstances, how they can support policy uptake and how experts and policymakers can work across different fields and knowledge systems. Drawing on a 2025 workshop of the Global Governance Innovation Platform (GGI) and contributions from four scholars, it considers how new SPIs can build on experience while remaining fit for purpose across different global challenges.