“Fragility”—the combination of poor governance, limited institutional capability, low social cohesion, and weak legitimacy—leads to erosion of the social contract and diminished resilience, with significant implications for peace, security, and sustainable development. This study reviews how the international community has responded to this challenge and offers new ideas on how that response can be improved. Based on that examination, the author seeks to convey the importance of addressing this phenomenon as a high priority for the international community. Chapters explore the nature of these obstacles to sustainable development, peace, and security; how the international community has defined, measured, and responded to the phenomenon of fragility; how the international response might be made more effective; and implications for the United States.