This chapter provides background on United States policy on R2P, and examines four key challenges going forward: (1) Policy prioritization: how high a priority to make R2P relative to other major interests? (2) Bureaucratic institutionalization: what policy-making and implementation entities need to be created and/or adapted? (3) Strategy: even if made a priority and institutional-organizational changes are made, what are the crucial elements for an effective atrocities prevention strategy? (4) International collaboration: what role should the United States play within the United Nations and more broadly internationally on R2P? The chapter speaks to both the scope and limits of progress that has been made, analyses the problems encountered, and argues for further US efforts in its own policy and its international role to advance R2P as norm and strategy.