Never before has blackstart power restoration been more vital for national resilience. At the same time, our capabilities to conduct blackstart – restarting the electric grid from inside the blacked-out area – have never been at greater risk. This Handbook provides electric grid operators, their government counterparts, and other stakeholders with recommendations to strengthen the survivability of blackstart systems and thereby help ensure societal continuity in the face of the most severe power outages. These ‘Black Sky’ events are defined as widespread, long-duration electric power outages and cascading failures of other critical infrastructures (water, communications, finance, transportation, etc). To save and sustain lives when these catastrophic outages occur, it will be essential to have robust blackstart capability. This handbook contains comprehensive analysis and recommendations from experts throughout the electric power sector, government, academia, and other sectors and organizations. It provides findings and recommendations for enhancing resilience in a sustainable, expanding grid environment.