Enforcement of agreements can be a major challenge in international politics. However, the interest in mechanisms of self-enforcement seems significantly lower among scholars studying international peace agreements (IPAs) than among scholars studying international environmental agreements (IEAs). Moreover, practically no exchange of ideas and findings about enforcement can be found between these two fields of research. We argue that a combination of similarities and differences between the two issue-areas provides fertile ground for mutual learning. To facilitate communication we develop a unifying but differentiated definition of self-enforcing agreements (SEAs). We then use this conceptual framework to explore lessons about IEA design that might be learned by studying IPAs and lessons about IPA design that might be learned by studying IEAs. We submit that this kind of compare-and-contrast analysis may provide important input for the development of a more refined and general theory of SEAs.