This chapter engages in an examination of the international legal underpinnings of R2P’s Pillar 2 responsibility for the international community to provide assistance and support to host States in meeting their Pillar 1 obligations. Noting that international norms and opinio juris underlying this pillar are significantly less developed than those of Pillar 1, this chapter considers emerging trends within international human rights law and international environmental law regarding a duty to cooperate and stipulates whether and how such obligations can come to be accepted as part of R2P.