The paper shows that both in environmental and in international health governance differential treatment norms can be identified. Moreover, in both issue areas differential treatment norms have become more pervasive and more fine grained over time. The evolution of differential treatment norms can be linked to world political transformations across both issue areas although it has to be noted that environmental governance consolidated only in the 1970s as a distinct issue area. Nevertheless, there are also important differences between the two issue areas regarding the categories of differential treatment that can be found in each of them and regarding the degree to which the norms are explicitly stated and legally codified.