This chapter determines regime constellations pertaining to Plant Genetic Resources for Food and Agriculture (PGRFA) management. The first three Cs in the Six Cs Model on the Measurement of Aggregate Regime Effects stands for coverage, compatibility and conduciveness. Regime interaction affects: regime constellations at the international level; their effects in developing countries. The chapter identifies the development stages of various regimes, and dynamics of interaction between regimes at various development stages to analyze the time dimension. There are normally five development stages: agenda-setting phase, negotiation phase, adoption of agreement and ratification period, implementation phase, and review/evaluation phase. The chapter identifies the main driving forces behind the various regimes and how they affected regime formation in the widest sense by concidering the historical analysis. In the context of the time dimension and mechanisms of influence, forum shopping is highly relevant, as it reveals where political 'clout' is vested from time to time an important factor for regime constellations.