International environmental agreements require negotiation and cooperation among countries. This paper attempts to analyze the presence and nature of inter-country interactions in the process of ratifying such agreements. We develop a theoretical argument based on the notions of strategic substitutability and strategic complementarity and study the interactions among three different peer types: geographic neighbors, trading partners and green investment projects partners (in our case, clean development mechanism projects partners). We test for the presence of interactions by taking into account a temporal dimension, which constitutes a methodological contribution. To this end, we introduce spatially lagged endogenous variables into a parametric survival model and apply the proposed framework to the Kyoto Protocol ratification process. Our data sample covers 164 countries for the period 1998 to 2009. We find evidence that, while countries’ ratification decisions are basically strategic substitutes, they become strategic complements once we focus on the ratification decisions of specific peers.