Capacity-building projects can be a vehicle for fostering policy diffusion. They should not, however, be considered as exclusively externally driven; the receiving jurisdiction’s receptiveness and leverage to steer the design of those projects can be crucial factors, shaping the process of infusing different external policy expertise and experiences into domestic policy design and implementation. This article shows that the Chinese National Development and Reform Commission (NDRC) has played a key role in steering the capacity-building efforts of external financiers in the case of greenhouse gas (GHG) emissions trading. The focus here is twofold: analyzing, on the one hand, the interaction among capacity-building projects financed by different external financiers, and on the other, the role that central actors and brokers can play in the complex structure of interacting projects.