This chapter focuses on regime overlap, interaction and the resulting regime constellations with which developing countries. It overviews the driving forces behind the international regimes and their mechanisms of influence, as a base for the analysis. The chapter analyzes the overlaps and interaction between the International Undertaking on Plant Genetic Resources (IU)/International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA) and the Convention on Biological Diversity (CBD). It then turns to the CBD and Trade Related Aspects of Intellectual Property Rights (TRIPS)/International Union for the Protection of New Varieties of Plants (UPOV). The chapter also turns to TRIPS/UPOV and the IU/ITPGRFA. For each set of regimes, it overviews the interaction between the two regimes in a time perspective, seeking to identify synergies, barriers and strategic opportunities. The chapter draws the findings on the resulting overall regime constellations with regard to PGRFA management and derives assumptions on what are expected to be the aggregate effects for developing countries.