Capacity building has been identified as being of importance for the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). As the IPBES is becoming an influential expert organization, it is essential to examine what capacity building means in its context, what capacities it has built, and what implications these capacities have. This study explores these issues by focusing on the IPBES's general strategy for capacity building, the IPBES's fellowship programme and to what extent there are additional capacity building needs that can be addressed. The study shows that the IPBES has focused its capacity building efforts on the science side of the science-policy interface while, thus far, it has neglected to build capacities on the policy side of the interface. The study provides insight into how capacity building for the science-policy interface sets preconditions for science-policy relations at different levels and scales within biodiversity and ecosystem services and beyond.